1 Introduction

Morphology is the study of word forms. Morphological parsers are computational tools that automatically produce a morphological analysis for a given word form. Such tools have proven to be quite useful as spelling checkers, as morphological grammar checkers, in producing interlinear text and in adaptation of a text from one related language to another. This document is designed to help the reader do morphological parsing using the approach allowed by Stage 1 of the FieldWorks Language Explorer parser. We also introduce issues related to the new experimental phonological rule-based parser, where appropriate.

The purpose of this documentation is to provide an introduction to the key concepts and notions in the FieldWorks Language Explorer approach to morphological parsing. It is divided into two main sections: morphotactics and morphophonemics. The first has to do with controlling which morphemes can co-occur with which other morphemes within a well-formed word. The second has to do with controlling the phonological shape of individual morphemes. (There are two other main sections; one deals with some issues related to lexical entries and the other to special considerations related to using compound rules.)

Please note that the mechanisms described here are the ones available for Stage 1, the first, rather simple-minded (linguistically-speaking) instantiation of FieldWorks Language Explorer. Later stages will provide much more power and capabilities.[1] The main reason why we have stages in the FieldWorks Language Explorer development project is to avoid trying to develop tools with all the user interface challenges all in one fell swoop. Doing that would be quite a daunting task and take a long time before any product could be released. Instead, we are staging the development to handle the basic items first. Then we'll add more and more as we go along.

As mentioned above, this document also introduces the new experimental phonological rule-based parser that you can try in addition to the default parser that has been available since day one of FieldWorks Language Explorer. The default parser is still the one that is documented here and is robust as far as we know. The new experimental phonological rule-based parser,[2] on the other hand, has yet to be thoroughly tested. So while our initial testing was encouraging, it may well have bugs and may not work as intended. If you choose to try it (and we would love to have you try it), we suggest you do so either on a copy of your main language project or on a small test language project. Please do report to us anything that you notice about this new parser that may help us make it be more effective. See appendix B for more on this new parser, as well as the subject index.

1.1 Key Issues

We begin by addressing some of the key issues that any general morphological parser must face. Before we can tell the computer what to do, we need to understand what is going on linguistically. What kinds of language phenomena must such a computational tool be able to handle if it will indeed be a general tool?

1.1.1 Inflection

Many, if not most, languages inflect verbs and/or nouns. Consider the nominal Orizaba Nahuatl forms shown in (1) and the verbal ones shown in (2).[3]

Notice how each possessed noun in (1) has at least a possessor prefix. Certain nouns require this possessor inflection. Similarly the verbs in (2) require subject markers (with the possible exception of 3rd person). A morphological parser must account for such inflectional items.

1.1.2 Derivation

Consider the English forms[4] in (3). What is happening here? How do you get a dumb computer to “understand” these forms correctly?

In (3a) institute is a verb root (e.g. We need to institute some changes around here.). By adding the suffix ‑ion as in (3b), the word is changed to a noun. The suffix ‑al can be added to a noun stem to change it to an adjective, as in (3c). The suffix ‑ize changes an adjective into a verb (3d). Further category changes occur with the addition of each suffix in (3e-g). From this English example, we have seen that the computer needs to be able to distinguish between roots and suffixes, with each one restricted as to what category it attaches to and what category it changes the stem to. (Note, for example, that the suffix ‑ly cannot be added to either a verb stem or a noun stem: *institutely, *institutionly.)

A Huallaga Quechua example showing similar category changes along with various types of verbal and nominal affixes is given in (4). The verb root meaning ‘to see’ has the imperfective aspect marker added, followed by the first person object marker, yielding ‘to see me.’ The addition of the nominalizer changes the form to a noun meaning ‘seeing me.’ The noun form can now be possessed by the second person possessive marker and then the purpose marker may optionally follow, finally giving ‘in order that you might be seeing me.’[5]

A morphological parser must account for such derivational items.

1.1.3 Ambiguity

Ambiguity is also apparent in (3a), since institute can be either a verb, as above, or a noun, as in Australian Institute of Marine and Power Engineers. Note that there are different types of ambiguity in natural language as well. For example, the word bank (among other things) can mean either the side of a river or a building that holds money. With either meaning, bank is a noun.

Now consider the following word:

Note that cooks is ambiguous not only in the root meaning but also as to the suffix: the -s is a nominal plural morpheme in (5a) but a verbal third person singular present tense morpheme in (5b).

A morphological parser must be able to deal with the fact that individual words can legitimately be ambiguous. That is, a morphological parser must be able to discover and report all possible analyses of a word form. In many cases, the ambiguity is eliminated when the word is seen in context, so ideally a morphological parser is used in the context of computational tools that look beyond a single word.

1.1.4 Epenthesis

There are still other types of challenges for morphological parsing. For example, consider the Caquinte word in (6):[6]

The (t) in two places on the second line (which shows the word broken into morphemes) are not really morphemes at all. Instead, they are epenthetic consonants added to serve as onsets to syllables. Caquinte does not allow vowel clusters nor syllables without onsets (in this part of the verb), so whenever two vowels come together at a morpheme break, an epenthetic t is inserted. A morphological parser needs to be able to correctly account for forms that include epenthetic segments inserted to preserve syllable structure.

1.1.5 Discontinuous Morphemes

Now consider the Caquinte form in (7), which is the same word as in (6), but changed to future tense:

What is the challenge here? The future tense is realized as a discontinuous morpheme: it is composed of the prefix n‑ and the suffix ‑e. The computer must be able to check these noncontiguous parts of the word to correctly analyze the future tense in Caquinte; one part cannot be present without the other.

1.1.6 Infixation

The Tagalog forms (from Spencer (1991:12-13)) in (8) illustrate another challenge:

What is happening here? This is a case of infixation, where the root sulat splits into two parts so that one of the focus morphemes, ‑um‑ or ‑in‑, can be inserted. A parser must correctly recognize the root even though it is broken apart by the infix.

1.1.7 Reduplication

Look at the additional Tagalog forms in (9) to determine how the imperfective aspect is marked:

We know from (8a) that sulat means ‘to write’. So in (9a) it appears that the imperfective marker is su, but we cannot tell if it is a prefix or an infix without looking at other forms. In example (9b) the causative ‘to make someone’ is the prefix pa‑. The mag‑ is what some call the actor focus or actor voice morpheme. But the imperfective of this causative form is not *sumagpasulat, *magsupasulat, nor *magpasusulat as we would expect from either prefixing or infixing su. Instead, we have magpapasulat in (9c) where it is clear that the marker for imperfective is the extra pa. The correct analysis is therefore that imperfective aspect is marked in Tagalog by reduplicating either the first syllable of the stem or the initial consonant and vowel of the first syllable of the stem.

A morphological parser must be able to recognize reduplication within a word form.

1.1.8 Root and Pattern Morphology

Semitic languages pose a special challenge with their root and pattern morphology. These languages have roots composed of three consonants, as exemplified in the Silt'i data in (10), where ‘buy’ is the root wkb. The aspect markers are composed of vowel patterns that fit between or around the root consonants, such as the a-a vowel pattern indicating the perfective aspect shown in (10). The parser needs to be able to find the root consonants and corresponding vowels of the aspect, even though they are intermingled in the surface form of the word.[7]

1.1.9 Metathesis

Now study the following Caquinte word.

What change takes place at the juncture between the final two morphemes? Notice that where one might expect the sequence keahi, what surfaces is kehai, where the h and a switch positions.[8] Such a transposition of phonemes is called metathesis. Furthermore, notice that the metathesis process in (11) crosses morpheme boundaries.

Such data imply that a morphological parser must be able to correctly identify morphemes even when some segments within the morphemes may have switched positions.

1.1.10 Morphemes that May Be Null

For a final challenge, consider these Caquinte forms (you do not need to understand all the morpheme glosses here; just concentrate on the initial subject prefixes):

What is the problem with the subject prefixes? In (12a) we see that the first person inclusive subject marker is a‑, and in (12b) the third person feminine subject marker is o‑. Yet, in (12c), the gloss shows ambiguity between ‘we’ and ‘she’ as the subject, and both of these are represented as null. This is because both subject prefixes are vowels and the stem in (12c) is vowel-initial, yielding two vowels together. Recall from (6) that Caquinte generally does not allow vowel clusters, and therefore adds an epenthetic ‑t‑ when necessary to avoid such clusters. It turns out that epenthesis is only used in the suffixes. Within the prefixes, the initial vowel of a cluster deletes, causing the ambiguity seen in (12c).

This means that a morphological parser must be able to identify a morpheme even when the morpheme has no overt segments.

1.2 Tasks for any Morphological Parser

Given the challenges of morphological parsing exemplified in the preceding section, how can a computer program go about analyzing words into their constituent morphemes? Let's say that the task of a morphological parser is to take a form like itsavetacojitiro from (6) above and

• see if it is a legitimate word,
• give an indication of which characters correspond to what morpheme, and
• produce an ordered list of its constituent morphemes (give glosses).[9]

What are some of the things our parser is going to have to know and what are some of the things that it is going to have to do?

Things the parser needs to KNOW:

• the forms and glosses of prefixes, infixes, roots, and suffixes,
• which of the affixes go with which roots,
• the relative ordering of the affixes, and
• when a particular shape of a form is legitimate and when it is not (allomorphy/phonology).

Things the parser needs to DO:

• find the affixes and root(s) in a given word, and
• check to see whether each affix can go with the rest of the word (that is, apply a set of constraints)

Clearly, properly using and controlling the constraints is the major task in implementing a parser for a given language. Since a morphological parser must model linguistic reality, it is a good idea to use constraints that model appropriate linguistic notions. Two major concepts for morphology are morphotactics and morphophonemics. Morphotactics deal with what morphemes can co-occur with what other morphemes. Morphophonemics deal with what shape a given morpheme will have in various phonological and morphological environments. The next two major sections outline the constraints available with the Stage 1 FieldWorks Language Explorer parser and how to use them.

2 Morphotactics

Morphotactics has to do with controlling the order of the morphemes in a well-formed word and controlling which morphemes can co-occur with which other morphemes. As examples of the former, one would not expect to find a prefix at the end of a word or a suffix at the beginning of a word. As an example of the latter, while one would expect a tense affix to appear with a verb root in a verbal word, one would not expect a tense affix to show up on a pronoun. The morphotactic mechanisms described in this section delineate what one can do within the FieldWorks Language Explorer model to control such things. The idea is to use the morphotactic mechanisms to correctly describe the facts of the language and thereby not only provide correct parses, but also rule out false parses.

By the way, correctly describing the facts of the language also provides the basis for a grammatical description, something that FieldWorks Language Explorer provides. By making a correct description of the facts we can both generate a description that people can read to learn about the language and we can feed the information to a parser that can put our description to work checking spellings, adapting to other languages, and verifying the fit of our description.

Note that for words which consist solely of a single morpheme, there are no special morphotactic considerations. One merely adds appropriate lexical entries for these and ensures that the morpheme type of the allomorph(s)[10] in the entry is(are) set to a root or stem type.

This section has four major sub-sections. The first deals with handling affixation to stems (section 2.1). The second deals with stem compounding (section 2.2). The third discusses issues related to clitics (section 2.3). The fourth is for those cases where the parser is producing parses that are incorrect, but the Stage 1 mechanisms do not allow any other way to eliminate the false parses (section 2.4).

2.1 Affixation

This section discusses issues relating to adding affixes to stems. Linguists typically divide affixes into two major categories: inflectional and derivational. Therefore, FieldWorks Language Explorer allows you to declare a given affix as being either inflectional or derivational. In the process of analyzing a language, however, sometimes one does not yet know whether a given affix is inflectional or derivational. There are certain affixes which are truly difficult to classify in this fashion. For this reason, FieldWorks Language Explorer also allows you to label a given affix as being unclassified with respect to inflection and derivation. As you study the language more, you should eventually figure out whether such affixes are inflectional or derivational and then you can change their status from being unclassified to the appropriate one.

2.1.1 Unclassified Affixes

You can label an affix as “unclassified” when you do not know if it is derivational or inflectional. Please understand, though, that when you do this, the affix is relatively unconstrained as to where it can appear. As a result, the FieldWorks Language Explorer parser may return a number of incorrect parses for some word forms which happen to contain a sequence of characters that match one or more allomorphs of an unclassified affix. One partial solution to this is to indicate the category of the stem to which the affix may attach. The best solution, of course, is to classify the affix as being either inflectional or derivational[11] so it will only show up where it should. See section 2.1.5 for more on how to determine if an affix is derivational or inflectional.

2.1.2 Inflectional Affixes

Inflectional affixes typically reflect what some call “grammatical meaning.” These are things like person, number, case, gender, tense, aspect, etc. One can also typically create a paradigm of word forms with the various inflectional categories as labels on the chart.[12]

2.1.2.1 Simple Example

For example, consider the information for a possessed noun in Orizaba Nahuatl given in (1) above, but this time displayed in a different fashion:

What are the inflectional affixes here? Given that every form has the sequence kal, it appears that there are six possessor prefixes which occur before the noun stem. Similar paradigms for other singular possessed nouns would show the same situation (ignoring any morphophonology). Therefore we could posit that the singular possessed noun has an inflectional template that consists of a possessor prefix followed by the stem. We could diagram this as in (14).

Now consider the plural possessed noun data from (1) above, but displayed in a similar fashion to (13).

What are the inflectional affixes here? Notice that there is the same stem (kal) and the same set of six possessor prefixes as in (13). In addition, there is a plural suffix ‑van. Similar paradigms for other plural possessed nouns would show the same situation (ignoring any morphophonology). Therefore we could posit that the plural possessed noun has an inflectional template that consists of a possessor prefix followed by the stem which, in turn, is followed by a plural suffix. Since plural is an instance of the notion of number, we could diagram this as an inflectional template as shown in (16).

Notice what we have described here: for a particular category (possessed noun), we have an inflectional template with one prefix slot (for possessor) and one suffix slot (for number). The possessor slot can be filled by any of the inflectional prefixes listed in (13). The number slot can be filled by the plural suffix.

Be aware that if you define a template that has no slots, then the parser will ignore that template. A template must have slots for the parser to use it. Similarly, if a slot has no affixes in it, that slot will also be ignored.

2.1.2.2 Optional Affix Slots

Now you may well have noticed that there is a potential problem here with the template in (16). If we treat each slot in the template as being obligatory, then the template says we must have a number suffix in order for the template to be satisfied. This means that a possessed singular noun will not meet the requirements of this template because it does not have a suffix in the number slot. It turns out that FieldWorks Language Explorer actually does treat each slot as being obligatory unless it is overtly marked as being optional.

What can we do about this? There are at least three options available within the FieldWorks Language Explorer approach:

1. Treat the Number slot as being optional so that for the singular case, there would not be any suffix in the Number slot.
2. Create two distinct templates for the possessed noun category: one for singular and one for plural.
3. Create a null singular number suffix which could then satisfy the requirement of something being in the Number slot.

Which of these three should we use? Options 1 and 2 will effectively give the same result, although option 1 is definitely simpler. Following the general principle known as Occam's Razor,[13] option 1 is thus better.

Option 3 requires us to posit a null suffix and some argue that if an affix is always null (as it would be here) then what we really have is a default feature: unless there is an overt number suffix, assume that the number is singular. While Stage 1 of FieldWorks Language Explorer does not allow us to mark such default features, later stages of FieldWorks Language Explorer will.

Therefore, from a long term perspective, we recommend following option 1.

This means that to model this inflectional template, we will need to do the following:

Once we have done this, we will have successfully set up the inflectional morphotactics for possessed nominals in Orizaba Nahuatl.

2.1.2.3 Multiple Templates

In the previous section we suggested that using optional affix slots in a template was a good choice for handling Orizaba Nahuatl nominal possession. Since we noted that within the FieldWorks Language Explorer approach, one could add more than one template to a category, one might wonder when it would be appropriate to choose such an option.

Orizaba Nahuatl happens to provide such a case. Consider the information for an intransitive, present tense verb given in (2) above, but this time displayed in a fashion more conducive to our purposes here:

What are the inflectional affixes here? At least under one analysis, there are four subject prefixes and a plural suffix. Third person subject is the default or is null. Similarly, singular number is the default or null.

Where do these inflectional affixes appear? Notice that all the subject ones appear just before the stem and that the plural suffix appears right after the stem. Similar paradigms for other intransitive verbs would show the same situation (ignoring any morphophonology). Therefore we could posit that the present tense, intransitive verb has an inflectional template that consists of a subject inflectional affix followed by the stem which is followed by a number inflectional suffix. We could diagram this as in (19).

At first glance, this is very much like what we saw for possessed nominals in example (16) above. We might think initially that we can do exactly what we did for possessed nominals and merely mark the Number slot as optional for these intransitive verbs. If we were to do that, however, notice what would happen for a form like timiki which is supposed to only mean ‘you(sg.) die.’ Because the Number slot would be optional, the FieldWorks Language Explorer parser would allow a parse of 1PlSubj-to.die as well (this, of course, is because both 2SgSubj and 1PlSubj have the same shape: ti‑). At this point, we would have nothing to prevent this incorrect parse.[14]

To eliminate this problem (as well as to eliminate the possibility of the parser allowing a parse for an ill-formed word such as *anmiki), we can create two inflectional templates: one for singular and one for plural. The singular one will be like this:

The plural one will be like this:

Notice how this method places the singular subject markers in the singular template and puts the plural subject markers in the plural template. This way we force the presence of the plural suffix for the plural subject prefixes.

What needs to be done to handle the 3rd person cases? We will need to mark the subject slot as optional in both templates in order to allow for the 3rd person cases.

This means that to model this inflectional template, we will need to do the following:

2.1.2.4 Discontinuous Morpheme

In section 1.1.5 above, we noted that in Caquinte, the future tense is realized as a discontinuous morpheme: it is composed of the prefix n‑ and the suffix ‑e. We repeat the example here:

How do we fulfill this requirement that both the future prefix and future suffix appear? One way is to create a future tense inflectional template which has both the prefix and the suffix required. The template might look like this:

Another possible way to treat discontinuous morphemes when one part appears before the stem and the other appears after the stem is to treat them as a single circumfix entry. See section 4.3.

2.1.2.5 Inflection and Categories Considerations

The categories in FieldWorks Language Explorer are organized in a hierarchical fashion. For example, one can have a major category of verb and then nest other verb types underneath it (e.g. intransitive verb, transitive verb, etc.) One can even nest other types under these if one so wishes (e.g. one might put bitransitive verb under transitive verb.).

The exact hierarchy one uses can make a difference for how the FieldWorks Language Explorer parser handles the inflectional templates and their slots. For templates, when you define an inflectional template for a given category, that template will be tried for any stem of that category or a stem of any of its nested categories. If, for example, you have intransitive verb and transitive verb nested under verb, then any inflectional template you define on verb will also be tried by the FieldWorks Language Explorer parser for any intransitive verb or transitive verb stem. On the other hand, in this scenario, any inflectional template defined under intransitive verb will only be applied to intransitive verb stems and any inflectional template defined under transitive verb will only be applied to transitive verb stems.

Thus, you can capture generalizations about the inflectional templates by placing common inflectional templates higher in the hierarchy.

Inflectional affix slots behave similarly with respect to the hierarchy: when one defines the slots for a given category, those slots may be used in any template for this category and any of its nested categories. For example, if all of your verbs share a common subject slot, then you can define this subject slot at the main verb category. This slot will then be available for any affix templates in all sub-categories of verb.[15]

You may well need to keep this in mind as you design your category hierarchy.

2.1.2.6 Inflection Classes

We now turn to something that is actually about morphophonemics, not morphotactics. We include it here, though, because it relates to inflectional affixes.

Consider the Yalálag Zapotec data given in (25)‑(26):[16]

What is the phonological shape of the Future marker? It appears to be u‑ in (25) but the “fortifier” segment/feature :‑ (i.e. a colon) in (26). Notice that there do not appear to be any phonological reasons for the different allomorphs. In fact, the stem has the same phonological shape in (25a) and in (26a).[17] This problem is not isolated to these pairs of forms; it turns out that verb stems in general divide into two groups, those that take the u‑ future and those that take the :‑ future.

How do we handle this kind of allomorphy when the choice of allomorphs is not motivated by the phonological environment but by the choice of the lexical stem? The FieldWorks Language Explorer approach is to use inflection classes. An inflection class is “a set of lexemes whose members each have the same type of inflectional forms” Aronoff (1994:64). They correspond to the traditional idea of declension classes or conjugation classes. For Yalálag Zapotec, we would create two inflection classes at the top-level verb category (so that it applies to verb and all sub-categories of verb; see section 2.1.2.6.2). One class would be for stems that select the u‑ allomorph and the other would be for those that take the “fortifier” :‑ allomorph.

This means that to model these inflection classes, we will need to do the following:

Now consider the following Latin data which also illustrates the use of inflection classes.[18]

Note that while there are five distinct declensions in Latin, there are only three forms for the dative plural: ‑is, ‑ibus, and ‑ebus. In particular, notice that ‑is is used for both declension class I and II and, similarly, ‑ibus is used for both declension class III and IV. So to model this Latin data in FieldWorks Language Explorer, we will need to do the following:[19]

Note that one can also set the default inflection class to be one of the inflection classes. If you do this, the FieldWorks Language Explorer parser will use this default inflection class for any stem that is not overtly tagged with an inflection class.

In addition, if an affix entry has any inflection classes and at least some of the allomorphs are constrained with environments (as described in section 3.1.3), one should be careful to tag all allomorphs in the entry with the inflection class(es) they go on. Otherwise, some allomorphs without environments may be incorrectly constrained.

2.1.2.6.1 Inflection Subclasses

Now we consider one more situation where inflection classes are appropriate. Like Yalálag Zapotec, Isthmus Zapotec also has verbal inflection classes.[20] There is a distinction, however. First, consider the data in (30)-(33), paying attention to the aspect prefixes.

Habitual aspect:

Progressive aspect:

Unreal aspect:

Future aspect:

Notice that based on this data, there are two inflection classes as summarized in (34).[21]

Second, when we consider two other aspects, things are not so straightforward. The stems are presented in the same order in (35)-(36) as they were above in (30)-(33):

Completive aspect:

Potential aspect:

For example, while the habitual prefix in (30b) differs from the one in (30a), they are the same for completive aspect in (35b) and (35a). Further, the potential aspect is quite different in (36d). How can we understand this data?

At least one way to understand this data is to posit two main inflection classes where one of these has three subclasses. We can summarize the affix allomorphy as shown in (37).

Finally, there is the Perfect aspect which has the same shape for all verbs as illustrated in (38).[22]

To model this Isthmus Zapotec data in FieldWorks Language Explorer, we will need to do the following:

In general terms, here is how the FieldWorks Language Explorer morphological parser will constrain an inflectional affix allomorph tagged for inflection classes when there are both main level classes and subclasses for at least one main level class:

Finally, please recall that if an affix entry has any inflection classes and at least some of the allomorphs are constrained with environments, one should be careful to tag all allomorphs in the entry with the inflection class(es) they go on. This may need to include subclasses. Otherwise, some allomorphs without environments may be incorrectly constrained. For example, if the allomorph conditioned with an environment goes on a subclass and an unconditioned allomorph is tagged with a main level inflection class, you will need to change the unconditioned one to go on all subclasses. This is because of condition 2b in (40) above.

2.1.2.6.2 Inflection Classes and Category Organization

As we noted in section 2.1.2.5, the categories in FieldWorks Language Explorer are organized in a hierarchical fashion.

The exact hierarchy one uses can make a difference for how the FieldWorks Language Explorer parser handles inflection classes. When you define an inflection class (or an inflection subclass) at a particular category in the hierarchy, then that class is available to be used for any lexical item associated with that category or any of its nested categories. Thus, you will probably want to define your inflection classes at the highest appropriate level in the hierarchy in order to capture generalizations.

2.1.2.7 Agreement and other Inflection Features

Consider the Spanish noun data given in (41) below:

Notice that the main difference between these nouns is the gender agreement suffix. If the ‑a ‘Feminine’ suffix is used, then the cas root means  ‘house’. On the other hand, if the ‑o ‘Masculine’ suffix is used, then the cas root means  ‘case’.

For a human, it is not necessarily difficult to keep these facts straight, but for a morphological parser, we need some way to prevent it from thinking that casa has the masculine root cas that means ‘case’. Similarly we need a way to keep the parser from thinking that caso has the feminine root cas that means ‘house’. That is, we need a way to prevent the parser from giving “analyses” such as the ones shown in (42), where the asterisk (*) indicates that the analysis is incorrect.

With the FieldWorks Language Explorer parser we use inflection features to deal with this issue. Inflection features are typically characteristics of a morpheme that play a role in the inflection of a word and/or play a role in the syntax (such as agreement within a noun phrase or agreement between a verbal affix and the noun phrase it agrees with). Note that if you use the Morphological Glossing Assistant tool for glossing inflectional affixes, then FieldWorks Language Explorer will automatically add some inflection features for you.

Coming back to the Spanish data in (41) and (42) above, how exactly does one use inflection features to rule out incorrect parses such as the ones in (42)? The problem here is that there is a mismatch between the gender of the root and the gender of the affix. If we can mark the root for the correct gender and also mark the suffixes for the gender they agree with, then the FieldWorks Language Explorer parser will only produce the correct parses.

Many languages will use one or more of the inflection features listed in the chart shown in (43) below.

These are just some examples. Your language may use these or may need others. You may want to check with a linguistic consultant who is familiar with your language family for ideas as to which inflection features are appropriate for your language. Or you may just want to add them only when you find a need for them, such as when the FieldWorks Language Explorer parser gives incorrect parses for forms.

The features shown in (43) are all simple features. There are times when a given word could contain more than one such set of simple features. This is where complex features are important. For example, for cases where a noun has noun class, say, and in addition, has a possessive affix which has a different noun class, then we must be careful to avoid the two noun classes from clashing with each other. If we merely use a simple inflection feature of “Class” for both the noun and the possessive affix, then the values will differ and the parser will not analyze the word. Instead, we need to use separate noun agreement and possessor agreement complex features. Within each of these complex features, we use the “Class” feature and its values. In this way, not only does the parser correctly analyze the word (because the two complex features do not clash), it also will have the correct features demarcated for eventual syntactic analysis.

Another possible example for the use of complex features is when a verbal word has both subject and object agreement markers in it. If the person features are different for subject and object, then we need to be sure and use two complex features, one for the subject agreement features and the other for the object agreement features.

The Spanish data illustrates how we can use gender inflection features to rule out incorrect parses when a gender affix shows up incorrectly on a root. Some possible situations where inflection features could play a similar role in ruling out incorrect parses include those shown in (44).

How does one create and use an inflection feature in FieldWorks Language Explorer?[24]

2.1.2.8 Inflection Classes versus Inflection Features

When modeling a given language, one may well wonder if a given phenomenon should be handled by inflection classes or by inflection features. Here are some guidelines to help one decide:

Look at the various affixes involved.

2.1.2.9 Underspecified Inflectional Affixes

In the above, we discussed how one can fully specify inflectional affixes. Sometimes it is the case, though, that you are confident that a particular affix is inflectional, but you just do not yet know the category it goes on. Or it might be the case that you know the category, but you do not yet know what the template looks like so you cannot put it in an inflectional affix slot.

FieldWorks Language Explorer allows you to model what you know. That is, you can still label such an affix as being inflectional, but only partially specify the rest of the information about it. If you know the category, but not the slot, you can say so. Be advised, though, that when you do this, the FieldWorks Language Explorer parser will treat such underspecified inflectional affixes just like it does for “unclassified” affixes (see section 2.1.1).

2.1.3 Derivational Affixes

Derivational affixes typically reflect what some call “lexical meaning.” They go on a stem to produce a new stem. The new stem may then be inflected (if the category of the new stem has inflection). Derivational affixes often change syntactic category. See Bickford (1998:135ff) for more on this.

2.1.3.1 Major Category-changing Derivational Affixes

The English data from example (3) is repeated below with more information:

What do we have here? We have five derivational suffixes, each of which changes the major category of the resulting stem. Recall that these suffixes only go on stems of a certain category. For example, the ‑al suffix only goes on noun stems. It does not go on other stems (*institutal, *institutionalal, and *quicklyal). These affixes are summarized in (47) below.

How do we model these category changing affixes in FieldWorks Language Explorer? We need to do the following:

2.1.3.2 Sub-category-changing Derivational Affixes

Now consider the pairs of data in (49)-(51) from Turkish:[27], [28]

What is the key difference in each pair? It is the addition of the passive morpheme. Notice how the number of arguments changes from two (subject and object) to one (just subject) with the addition of the passive.

Is passive, then, a category changing derivational affix? While it does not change major category (i.e. it does not change a verb into a noun, say) it does change a transitive verb into an intransitive verb. That is, passive is a case where the sub-category is changed. Many languages have other such sub-category changing derivational affixes such as causatives, applicatives, and transitivizers. As far as FieldWorks Language Explorer is concerned, these are category changing derivational affixes since the result of the derivation produces a different sub-category that potentially requires a different inflectional template to complete the word form.

How do we model these sub-category changing affixes in FieldWorks Language Explorer? We need to do the following:

2.1.3.3 Non-category-changing Derivational Affixes

Now consider the following Yalálag Zapotec data:[29]

The addition of the repetitive prefix does not change either the major category or the sub-category of the words in (53)-(54). One might wonder, then, if the repetitive in Yalálag Zapotec is actually an inflectional prefix. The evidence that it is derivational is that it actually changes the inflection class of the resulting stem. As we saw in section 2.1.2.6, Yalálag Zapotec verbs have two inflection classes. In (53a) the stem is inflection class 2 (because it takes the “fortifier” :‑ allomorph of the future prefix). After the a‑ repetitive prefix is added in (53b), the resulting stem uses the inflection class 1 allomorph of future (u/w‑).

How do we model these non-category changing affixes in FieldWorks Language Explorer? We need to do the following:

Notice that in this case the from‑ and to‑ categories will be the same, but we do need to deal with the change in inflection class. This leads us to the next topic below.

2.1.3.4 Inflection Class and Derivational Affixes

If the language you are studying has inflection classes (see section 2.1.2.6), then what happens when derivational affixes are attached? Does the inflection class of the stem stay the same or does it change?

2.1.3.4.1 Inflection Class May Change

As we saw from the Yalálag Zapotec data in 2.1.3.3, the inflection class can indeed change. How do we model this? In addition to what we've done for the categories, we need to do the following:

Note that rarely, if ever, does one need to indicate the “from inflection class” information. We include it in case you do find that you need it.

2.1.3.4.2 Inflection Class Does Not Change

There are cases, though, where a derivational affix is attached and it does not change the inflection class of the resulting stem. For example, consider the following data from Atzingo Popoloca:[30]

The applicative suffix Apl adds an argument to the verb, but it does not change the inflection class of the resulting stem. The root in (57) belongs to inflection class 1 and so takes the t‑ allomorph of the present tense morpheme. Adding the applicative does not change this (57b). Similarly, the root in (58) belongs to inflection class 2 and so takes a null allomorph of the present tense. Once again, adding the applicative does not change the inflection class of the resulting stem (58b).

To model this in FieldWorks Language Explorer, one does the following:

2.1.3.5 Inflection Features and Derivational Affixes

If the language you are studying has inflection features (see section 2.1.2.7), then what happens when derivational affixes are attached to a stem with, say, agreement features? Or what happens when a derivational affix changes the category of the stem to a category that has agreement features? For example, consider the Spanish data in (60) and (61):[31]

Here we have a verb (e.g. apretar) and a noun derived from that verb (e.g. apretón). Recall from section 2.1.2.7 that Spanish nouns are marked for gender (masculine or feminine). While Spanish verbs are not marked for gender, a noun derived from a verb will have gender. In the case of the ‑ón derivational suffix, the resulting noun has masculine gender. To properly model this, we would need to indicate that the resulting noun has this gender.

How does one mark a derivational affix for inflection features in FieldWorks Language Explorer?

2.1.3.6 Category-changing Derivational Affixes and Category Organization

As we noted in sections 2.1.2.5 and 2.1.2.6.2, the categories in FieldWorks Language Explorer are organized in a hierarchical fashion.

The exact hierarchy one uses can make a difference for how the FieldWorks Language Explorer parser handles the categories of derivational affixes. When one indicates the “from category”, the FieldWorks Language Explorer parser will allow the derivational affix to apply to stems of this category and any of its nested categories. You may well need to keep this in mind as you design your category hierarchy.

You can use the hierarchy to capture some generalizations. For example, suppose your language has a nominalizing derivational affix that can attach to any verb stem, resulting in a noun stem. Further, suppose that the top-level verb category has two sub-categories: intransitive verb and transitive verb. If you mark the “from category” as being verb, then this affix can attach to a verb stem, an intransitive verb stem, or a transitive verb stem.

Sometimes, however, the hierarchy implies that one will need to have more than one mapping for a given derivational affix. For example, one might need a causative to map as follows if the inflectional templates are different for intransitive verb, transitive verb, and ditransitive verb:

To do this, you need to add a separate mapping for each possible from/to pair. You do that by adding distinct senses and associating each sense with the appropriate mapping.

If a derivational affix only changes meaning (i.e. it does not change the category or the sub-category), then one can use the highest level category for both the “from category” and the “to category”. In this case, the FieldWorks Language Explorer parser will pass on the (sub-)category of the stem to which the derivational affix attaches as the resulting category of the new stem. For example, if one chooses to model an adverbial affix on a verb as being derivational, then if one marks both the “from category” and the “to category” as "verb," then when this affix attaches to an intransitive verb, the resulting stem will still be intransitive. If it attaches to a transitive verb, then the resulting stem will still be transitive.

2.1.3.7 Underspecified Derivational Affixes

In the above, we discussed how one can fully specify derivational affixes. Sometimes it is the case, though, that you are confident that a particular affix is derivational, but you just do not yet know the category it goes on or the resulting category after it attaches. Or it might be the case that you know either the category it attaches to or the category it results in, but not both.

FieldWorks Language Explorer allows you to model what you know. That is, you can still label such an affix as being derivational, but only partially specify the rest of the information about it. If you know the category it attaches to, but not the resulting category, you can say so. If you know the category it results in, but not the category it attaches to, you can say so. Be advised, though, that when you specify the category it attaches to, but not what the resulting category is, the FieldWorks Language Explorer parser will treat such an underspecified derivational affix just like it does an “unclassified” affix (see section 2.1.1). If, on the other hand, you do not say what category it attaches to, but do say what the resulting category is, the FieldWorks Language Explorer parser will treat it as if you had said that the derivational affix can go on every category.

2.1.4 Derivation Outside of Inflection

Derivational affixation tends to be close to the root. Since derivation sometimes changes the category of a stem, this is not surprising. Derivational affixes, then, normally occur inside of inflectional ones.

However, there are cases in some languages where a stem will be inflected, then a category changing derivational affix will be attached and the resulting stem will be inflected.

The Quechua example we saw in (4) is such a case. It is repeated below in (63).[5]

At least under one analysis, the verb root meaning ‘to see’ has the imperfective aspect marker added, followed by the first person object marker, yielding ‘to see me.’ We thus have a verb stem inflected with an aspect and an object marker. To this inflected form, the nominalizer derivational affix is attached, resulting in a noun meaning ‘seeing me.’ The noun form then has the second person possessive marker and the purpose marker added, finally giving ‘in order that you might be seeing me.’ That is, the resulting noun stem is now inflected by a possessive and a (kind of) case marker. We could diagram this process as in (64).

(64)

In (64) the Infl nodes represent inflected forms. Note how the derivational suffix ‑na changes the inflected verb into a noun stem (Stem[n]). This stem is then inflected.

It turns out that while the Infl[n] node is a fully inflected noun, the Infl[v] is actually only a partially inflected verb: It lacks a required subject suffix. That is, a form such as rikaykaamaa with the analysis of to.see‑Imp‑1Obj is ill-formed. Thus, the verbal inflectional template given in (65) is a special kind of template. It does not represent a fully inflected form. Rather, it requires that there be a derivational affix attached outside of the template in order for the word to be well-formed. When you have such templates, you will need to mark them as requiring additional derivation. The default situation is for the FieldWorks Language Explorer to assume that an inflectional template does not require additional derivation outside of the template.

How does one handle such derivation outside of inflection in FieldWorks Language Explorer? One needs to perform the following steps:

2.1.5 Derivation versus Inflection

Determining if a given affix is derivational or inflectional can sometimes be quite a challenge. Arguably, the range from derivational to inflectional is a continuum and there are some affixes which seem to “float” somewhere in the middle. Nonetheless, there are recognized criteria one can use to try and help one figure out which kind a given affix might be. These are not hard and fast rules, however.

Albert Bickford offers the following guidelines in helping one to decide (taken from Bickford 1998:139, including the note on productivity).

Tom Payne also has some suggestions about characteristics of derivational affixes. The following quote is taken from T.Payne (1997:42):

2.1.6 Exception “Features”

Even when one has correctly classified the affixes in a language as being derivational or inflectional, sometimes a morphological parser will find combinations of stem and affix that are simply incorrect. This may be due to historical or some other seemingly arbitrary reasons.

For example, consider the following Orizaba Nahuatl data:

Notice that in this data, the “Absolutive” suffix (which normally goes on singular, unpossessed nouns) appears to derive a noun from a verb. When one models this, one may find that other nouns which have the absolutive suffix now analyze as derived nouns. For example, one might get these:

The FieldWorks Language Explorer parser allows one to rule out such incorrect combinations via what have sometimes been called exception “features.”[34] The basic idea is to tag the affix with an exception “feature.”  The only time the FieldWorks Language Explorer parser will then allow this affix to occur is when the stem to which it attaches also has been tagged with the same exception “feature.” Thus you can restrict the productivity of the affix to only occur on certain stems. Note that this is only possible for affixes which have been fully classified as either being derivational or inflectional. Exception “features” are not available for unclassified affixes.

If a given affix has two or more exception “features,” then the stem to which it attaches must be tagged with all of the exception “features” that the affix has. Note that if an affix does not have any exception “features” but the stem to which it is being attached does have one or more exception “features,”  then the affix will still be allowed to attach (as far as the exception “features” are concerned).

To tag affixes and stems with exception “features,”  do the following:

2.2 Stem Compounding

This section relates to the compounding of two or more stems within a single orthographic word.[35]

There are two basic kinds of compounds: headed compounds (section 2.2.1) and non-headed compounds (section 2.2.2). We also discuss issues relating to incorporation (section 2.2.3), issues relating to compounding when stems contain affixes (section 2.2.4), and issues relating to the organization of categories (section 2.2.5).

2.2.1 Headed Compounds

Consider the following Orizaba Nahuatl data:[36]

What are the categories of the two members of the compound? The left one is an adjective and the right one is a noun. What is the category of the compound? It is a noun. Thus the examples in (71) show an adjective compounding with a noun where the result is the right member of the compound. Thus, we can say that the “head” of the compound is the right member of the compound.

Now consider the following Orizaba Nahuatl data:

In (72) the left member is a noun and the rightmost member is an adjective. Like in (71), the result is a noun. Thus the “head” of the compound is the left member in the cases in (72).

Both of these are instances of headed compounds. Either the left or the right member of the compound is the head of the compound. That is, the category of the resulting compound is the same as either the left or the right member of the compound.

How do we model these kinds of rules for Stage 1 of FieldWorks Language Explorer?

2.2.2 Non-headed Compounds

Now consider the following Spanish data:

Which member of the compound is the head? Clearly it is not the left member since the resulting compound in both cases is a noun and the left member is a verb. But is the head really the right member of the compound? While the right member is a noun, this noun is not inflected for the correct gender and/or number. Thus, these examples show the need for the other kind of compound rule: non-headed compounds. In non-headed compounds, the category and/or agreement features of the resulting stem are not merely the same as the head. Instead, the new stem may be something different.

To model this in FieldWorks Language Explorer, we do the following:

2.2.3 Incorporation

Some languages allow the incorporation of lexical roots within the stem. The resulting stem may or may not differ from the non-incorporated stem in terms of category and/or features. This means that if the language you are modeling has incorporation, you will need to consider whether to use a headed or a non-headed compound rule for it.

2.2.3.1 Incorporation as a Simple Headed Compound

Consider the following Yalálag Zapotec data:[37]

At least under one analysis, in (76b) the adverb to is incorporated onto the verb ej. In (77b), a different adverb, :cha:ch, is incorporated.

Notice that the resulting stem appears to have all of the characteristics of the verbal stem which is the left member of the compound as indicated by (76a) and (77a). Therefore, this kind of data can be modeled as a left-headed compound rule.

2.2.3.2 Incorporation as a Headed Compound with Override

Now consider the following Orizaba Nahuatl data:[38]

What is happening here? Notice how the nouns in (78a) and (79a) replace the 3Obj marker in (78b) and (79b) to produce the forms in (78c) and (79c). In particular notice that the resulting stem no longer requires a transitive verb inflectional template, but rather an intransitive verb one. We can say that this is because the noun has been incorporated as the object and the result is an intransitive stem. We can model this in FieldWorks Language Explorer as a headed compound, but override the category of the head stem. We could diagram it something like this (where “[vt]” means a transitive verb stem and “[vi]” means an intransitive verb stem):

(80)

becomes

That is, we create a right-headed compound rule and set the “Overriding category” in the rule to be an intransitive verb. The rule will use all the characteristics of the head stem except for the category. It will override the category of the head stem with the specified “Overriding category”.

2.2.4 Affixes Between Roots in Compounds

Consider the Wanca Quechua form given in (81) below:[39]

Here we have a (reduplicated) compound consisting of a root, a suffix, the same root, and the same suffix. This forms a compound as shown in (82):

(82)

In Stage 1 of FieldWorks Language Explorer, we must treat suffixes like ‑n in a special way. Affixes which can appear between roots in compounds we call “interfixes.” In order to tell the Stage 1 FieldWorks Language Explorer parser that a suffix like ‑n can appear in compounds like it does in (81), we must give it a morpheme type of “suffixing interfix”. This tells the Stage 1 FieldWorks Language Explorer parser that this suffix can appear either as a “regular” suffix (merely after a root) or as a suffix before another root in a compound. Note that it is the leftmost instance of ‑n that is crucial here.

There are three varieties of interfixes:

If the language you are modeling has these kinds of compounds and you want the parser to analyze them via a compound rule, then you will need to mark any affixes which can appear between roots with these special morpheme types.

2.2.5 Compound Rules and Categories Considerations

As we noted in sections 2.1.2.5, 2.1.2.6.2 and 2.1.3.6 above, the categories in FieldWorks Language Explorer are organized in a hierarchical fashion.

The exact hierarchy one uses can make a difference for how the FieldWorks Language Explorer parser handles the categories in compound rules. When one indicates the information for a left or right member of a compound, FieldWorks Language Explorer will consider stems of this category and any of its nested categories to match. For example, if the main level verb category has two sub-categories of intransitive verb and transitive verb, then if a verb stem, an intransitive verb stem, or a transitive verb stem may be the left member, say, of a compound, you only need to say that the left member must be of category verb. The FieldWorks Language Explorer parser will allow the left member to be a verb stem, an intransitive verb stem, or a transitive verb stem. You can thus capture a generalization.

You may well need to keep this in mind as you design your category hierarchy.

2.3 Clitics

We turn now to consider clitics. Consider the Shipibo data below[40] and notice the ‑ra morpheme. Where does it occur and on what kinds of words does it appear?

In both (83) and (84), the indicative ‑ra morpheme appears at the end of the first word. In (83) it attaches to a subject and in (84) it attaches to the object.

This morpheme can also attach to other categories as the following examples demonstrate:

The ‑ra morpheme attaches to an adjective in (85), a postposition in (86), a verb in (87), and an adverb in (88). Notice that it actually appears at the end of the first constituent (a noun phrase in (85) and a postposition phrase in (86)).

Morphemes like this are often analyzed as being clitics. Orthographically, such clitics may be written attached to another word (like in Shipibo) or they may be written independently. In my experience, orthographic conventions vary on this point. If the clitic is written as attached, then it should be classified as a proclitic if it “prefixes” and as an enclitic if it “suffixes.” If the clitic is written as an independent word, then one may classify it as a clitic. Some orthographic conventions are such that what the analyst considers to be a proclitic or enclitic is also written as an independent word. In such cases, one may still give these a morpheme type of proclitic or enclitic. The FieldWorks Language Explorer parser will correctly handle a clitic that is labeled as being either a proclitic or enclitic whether it is written attached or as a separate word.

How do we model such clitics in FieldWorks Language Explorer?

FieldWorks Language Explorer will do the rest: such morphemes will be allowed to appear at the end (for enclitics which attach) or at the beginning (for proclitics which attach) of words. More than one clitic may appear on a single word. There is no ordering restriction between sequences of attached clitics (other than ad hoc rules; see sections 2.4 and 3.10).

A final note: if your orthographic convention permits several clitics to be written together as a single word (where every morpheme in that orthographic word is a clitic of some kind), then only one of the clitics may be marked as clitic. The others must be marked as proclitic or enclitic and these must be in the proper order (proclitics before the clitic and enclitics after the clitic).

2.4 Ad hoc Morpheme-oriented Rules

When one uses a morphological parser, it is not unusual for the parser to sometimes return a parse that is simply incorrect. These are sometimes due to allomorphs matching in places one would not have expected them to match. When one has used all the mechanisms provided by the parser to the best of one's ability and such incorrect parses continue to surface, one may well wish for some kind of mechanism to rule them out. FieldWorks Language Explorer provides “Ad hoc Rules” for such situations. Note that it may well be the case that later stages of FieldWorks Language Explorer will provide more well-motivated means to rule out these infelicitous parses, but for now, these ad hoc solutions may have to do.

2.4.1 Creating Morpheme-oriented Ad hoc Rules

There are two main types of ad hoc rules: morpheme-oriented ones and allomorph-oriented ones. This section deals with morpheme-oriented ones (see section 3.10 for allomorph-oriented ones). The basic idea is to list a key morpheme and then to list one or more other morphemes that cannot co-occur with the key one. One can constrain these other morphemes to never occur in one of the following ways with respect to the key morpheme:

Note that when there are two or more morphemes listed for “other morphemes,” the rule only applies when all of them co-occur in the same word with the key morpheme. In addition, their relative order is significant. They should be listed in the same linear order they occur in a word.

How does one create a morpheme-oriented ad hoc rule in FieldWorks Language Explorer?

2.4.2 Grouping Ad hoc Morpheme Rules

Occasionally one finds a situation where a set of ad hoc constraints have a common theme. Perhaps they all relate to a particular morpheme or to particular morphemes of a certain variety. This may be a hint as to what is really happening and may lead you to discover a linguistically-motivated way to model them. Or it could be that the FieldWorks Language Explorer model (or the currently implemented stage of FieldWorks Language Explorer) just does not happen to provide the appropriate linguistic mechanism to model the phenomenon correctly.

Yalálag Zapotec dependent pronominal suffixes exemplify such a situation (see López y Newberg 1990:9). In Yalálag Zapotec, a verb may have both a subject and an object person suffix on it. Being a VSO language, the subject occurs before the object. What is different here is that there is a pronominal hierarchy among these dependent pronominal suffixes. Given the subject suffix, the only dependent object suffixes which may follow are those that are lower down on the person hierarchy. This is illustrated in (92).

How would one model such a hierarchy in FieldWorks Language Explorer? Well, one could create a number of different transitive verb inflectional templates in order to force the hierarchy to come out. But this does not really capture the facts all that well and also complicates and obscures what is common in the transitive verb template. (By the way, neither the subject nor the object is required to be filled by a suffix.) Probably the better approach is to create a morpheme ad hoc rule group and place the set of appropriate ad hoc rules for the hierarchy in that group. This way one can document the fact of the hierarchy and have it all in one place. It also documents the fact that the FieldWorks Language Explorer model does not have an overt mechanism to deal with such a hierarchy.

How does one create such a group?

Finally, note that FieldWorks Language Explorer allows one to group both allomorph and morpheme ad hoc rules together. Please be sure to only do so if these rules truly do have something in common.

3 Morphophonemics

Besides constraining the overall positions where morphemes can occur (i.e. deal with morphotactics), we need to be able to account for the surface forms that the morphemes have and the particular environments where an allomorph is legitimate.

3.1 Overview

Consider the following Orizaba Nahuatl data:

What are the shapes of the 1SgSubj and the 2SgSubj allomorphs? The first person singular subject marker appears to be ni‑ before consonants and n‑ before vowels. Similarly, the second person singular subject marker alternates between ti‑ and t‑.

How can we encode this information? There are at least two ways to deal with such phonological information:

1. Give the underlying form along with a set of rules to create the surface forms; or
2. List the surface allomorphs and condition each one to appear in the appropriate surface environment.

Generative phonology uses the first approach (also known as the item and process approach, Hockett (1954)). For example, given the data in (94), one might consider the underlying forms of the two subject prefixes would be ni and ti, respectively. We would then write a phonological rule to delete the first vowel when it is followed by a second vowel.

Stage 1 of FieldWorks Language Explorer, however, chooses the second approach (also known as the item and arrangement approach, Hockett (1954)). For example, once again considering the data in (94), we would need two forms for each subject prefix entry. We could make the Lexical Form be the longer one (ni and ti, respectively) and have an allomorph for the shorter one (n and t, respectively) that would be conditioned to have an environment saying that it must be followed by a vowel.

Plans for Stages 2 and 3 of FieldWorks Language Explorer include also allowing the first.[42] As noted in section 1, we now also have the new experimental phonological rule-based parser which allows for both item and arrangement and item and process. See appendix B for more.

For Stage 1 of FieldWorks Language Explorer, then, the basic mechanism available is to list surface allomorphs and then have the option to constrain individual surface allomorphs by their environment. To define an environment, one may well want to use natural classes of segments (e.g. consonant, vowels, voiceless stops, nasals, etc.). To define such natural classes, we need to know what the possible segments are.

3.1.1 Phoneme Sets

In order to use environments which refer to phonemes or which have natural classes, you need to create a list of all the phonemes in your language. For each phoneme, you need to indicate one or more representations that represent them. For example, in Greek, the /s/ phoneme has two such representations: ς (which is used word finally) and σ (which is used everywhere else).

In addition to these phonemes, you may also need to refer to word boundaries in an environment. For this reason, Stage 1 of FieldWorks Language Explorer comes with a predefined word boundary marker: the # symbol.

Stage 1 of FieldWorks Language Explorer also comes with a potential set of phonemes already defined. That is, you do not need to start from scratch when building the list of phonemes for your language. However, you may well need to edit the list of phonemes initially included for a new language project. This initial set of phonemes is given in (95) below.

To define the set of phonemes for the language you are modeling, do what is shown in the following:

3.1.1.1 Digraphs

If you have orthographic digraphs (or trigraphs) as phonemes, you follow the same basic steps outlined in (96) steps 3 and 4. Merely use the appropriate digraph for the phoneme and also use the digraph as the representation/grapheme. For example, if you have an aspirated voiceless alveolar stop written as th, then use th for the information.

3.1.1.2 Tones

While many languages have tones, not all mark the tone in the practical orthography. If the language you are modeling includes tone symbols marked on vowels as accents, say, then you need to decide which of several ways to go in indicating tone.

3.1.1.2.1 No Forms Conditioned by Tone

This is the simplest case where no forms are ever conditioned by surrounding tone. For example, it is never the case that you have an affix which must be preceded or followed by a high tone (or low tone). Because of this, you never need to write an environment that refers to tone, only to natural classes of segments.

If this is the situation you have, then for each vowel that bears tone, add a distinct representation for how that vowel with tone is written. For example, when the vowel a has high tone, it is written as á, then you need to add á to the list of representations/graphemes for the vowel a.

3.1.1.2.2 Forms Conditioned by Tone

The second situation is more complicated. This is where there are forms in your language that must be conditioned by surrounding tone. For example, there is an affix form which is licit only if it is preceded or followed by a particular tone (high, say). This means that you will need to be able to write an environment that contains all phonemes that bear high tone. To do this, there are two options.

The first option is to have distinct phonemes for each high toned vowel, say. If this is your case, then you need to make distinct phonemes for each vowel that bears different tones. For example, if a low tone a is written as a while a high tone a is written as á, then you will need two phonemes: one for the low toned a and one for the high toned a. You can then create a natural class that contains all high-toned phonemes and write your environment in terms of this natural class.

The second option is to create phonemes that consist merely of the tone diacritic itself. Since FieldWorks Language Explorer always stores its data in “decomposed” form (NFD), any accent marks or other diacritics will be stored after the main symbol. Thus, á is stored as two characters aˊ, the /a/ and then the acute accent. Taking advantage of this, you could create a phoneme that is for the acute accent ˊ and call it something like “High tone.” You could then condition the forms to occur only when followed by this acute accent phoneme.

3.1.2 Natural Classes

Once you have the phonemes defined, then you can create natural classes of phonemes. Some common ones include such things as consonants, vowels, voiceless stops, back vowels, etc. To do this in FieldWorks Language Explorer do the following:

We highly recommend that you seek to give unique abbreviations for these. While it is possible to have two or more natural classes with abbreviations spelled exactly the same way, we do not recommend that you do so on purpose. Having two or more natural classes with the same abbreviation will not confuse FieldWorks Language Explorer because FieldWorks Language Explorer uniquely identifies every natural class internally. That does not imply, however, that either you or a reader of your grammar will not be confused as a result.

3.1.3 Allomorph Environments

Once the set of phonemes and natural classes are defined for the language you are modeling, you can define environments for allomorphs. You can add them either in the environment editor or with a given lexeme form or allomorph.

In Stage 1 of FieldWorks Language Explorer, you key these environments using a special notation. This notation is one that is reminiscent of what is used in many generative-style rules. The basic rules of thumb are:

Example (99) gives some sample environments along with what they mean.

For a similar table for right-to-left scripts, see this endnote.[44]

A given allomorph may have more than one environment, in which case the various environments are logically ORed with each other. That is, if any one of the environments for the allomorph are found, then the allomorph is considered to be valid (as far as its environments are concerned). For example, if a given allomorph can appear either before a consonant or word finally, then you can list both an environment for “before a consonant” and one for “before a word boundary.” Example (100) shows what this might look like, assuming that you have a natural class of consonants with an abbreviation of C.

Finally, if an affix entry has inflection classes as well as at least some allomorphs with environments, you should be careful to tag all allomorphs in the entry with the inflection class(es) they go on. Otherwise, some allomorphs without environments may be incorrectly constrained.

3.1.4 Allomorph Ordering

It is crucial to note that allomorphs are ordered in the sense that their respective environments are disjunctively ordered. For example, for the Nahuatl 1SgSubj allomorphs above in example (94), we could list the two allomorphs in any of the ways shown in (101)-(104).

Note in particular that for the two implicit methods, one does not have to overtly state the environment for the last allomorph. This is because each allomorph automatically inherits the negation of the environments of any preceding allomorphs. Thus, for the Implicit 1 method, the n is automatically treated as having an environment of "not before a consonant." Similarly, for the Implicit 2 method, the ni is automatically treated as having an environment of "not before a vowel." For more on this, see section 4.1.2.

3.1.4.1 Free Fluctuation

Sometimes a language has free fluctuation between two allomorphs of a morpheme. In such cases, one should create both allomorphs and condition them exactly the same way (in terms of environments and inflection classes). One should also order them one after the other. The FieldWorks Language Explorer default parser will try both forms in such cases.

3.2 Reduplication

In the next five sections, we will address five issues brought up in section 1.1. First, we deal with reduplication.

3.2.1 Full Reduplication

Consider the following data from Bahasa Indonesia:[45]

In examples (105)-(109) note that the entire word is reduplicated, no matter what its syllabic shape might be. This is what is often called full reduplication.[46]

In examples like (105)-(109), one cannot tell whether the reduplication morpheme is a prefix or a suffix. However, sometimes a stem will reduplicate and other affixes may be adjoined. For example, consider (110)‑(111):

Notice the ‑nya suffix which comes after the reduplicated stem. The way we are modeling full reduplication in FieldWorks Language Explorer, the root must be at one end and then any affixes (including the reduplication morpheme) must either be all prefixes or be all suffixes.[47] Thus, in modeling examples (110)‑(111), we would make the reduplication morpheme be a suffix.

3.2.1.1 Writing the Pattern for Full Reduplication (for Stage 1 of FieldWorks Language Explorer)

How do we indicate full reduplication for Stage 1 of FieldWorks Language Explorer? (See B.1.1.1.1 for how to write an affix process for full reduplication using the new experimental phonological rule-based parser.)

3.2.2 Partial Reduplication

As we saw in the Tagalog data from (9) from section 1.1.7, it is not always the case that the entire stem is reduplicated. The Tagalog data is repeated here.

Recall that we saw that this is a case where the imperfective aspect is realized by reduplicating the first CV syllable of the stem to which it attaches. (The mag- prefix is what some call actor focus or actor voice.)

Now consider the following Orizaba Nahuatl data:[50]

What is the reduplication pattern here? It is the initial CV of the stem followed by an h. Thus we see that in this Nahuatl case of reduplication, there is not only the copied material, but also some fixed segmental material.

The kind of reduplication illustrated in (113)-(115) above is often referred to as partial reduplication. How do we model such partial reduplication in Stage 1 of FieldWorks Language Explorer? (See B.1.1.1.2 for how to write an affix process for partial reduplication using the new experimental phonological rule-based parser.)

3.2.2.1 Writing the Pattern for Partial Reduplication (for Stage 1 of FieldWorks Language Explorer)

For Stage 1 of FieldWorks Language Explorer, we use a special notation to indicate a partial reduplication pattern.[51] The idea is to list a sequence of specially marked natural class names. The special marking consists of the following:

Suppose we have a natural class for consonants with an abbreviation of C and one for vowels abbreviated as V. Then the reduplication patterns for our Tagalog and Orizaba Nahuatl reduplication examples above in (113) and (114)‑(115) would be as in (118).

For the Orizaba Nahuatl case, notice the use of the h (the fixed segmental material) in the allomorph pattern. It is not included in the environment pattern for the simple reason that the h does not show up in the environment.

Note that if a language has a CVC reduplication pattern, then one would want to use a pattern of [C^1][V^1][C^2], where the distinct indices on the consonant natural classes makes it clear that they can be different.

3.3 Infixation

We now address another issue from section 1.1: infixation. We repeat here the Tagalog data from example (8) in section 1.1.6.

Recall that there are two focus morphemes here, ‑um‑ and ‑in‑, both of which are infixes.

How does one create such infixes in Stage 1 of FieldWorks Language Explorer? (See B.1.1.2 for how to write an affix process for infixation using the new experimental phonological rule-based parser.)

Note that infix allomorphs may be conditioned by regular environments just like any other allomorph. See section 3.1.3. With the Stage 1 parser, these environments should be with respect to what the environment is before the infix has been pulled out of the stem.

3.3.1 Writing the Infixation environment (for Stage 1 of FieldWorks Language Explorer)

Infix environments describe the location within the sequence of characters where the infix is to go.[52] For example, in (119), it would be within sulat between the initial s and ulat. The environment would then be / # [C] _ [V] where # indicates the beginning of the sequence within the stem, [C] is the natural class of consonants and [V] is the natural class of vowels. Note that with the infixation environment, the # does not indicate word boundary, but rather the beginning of the stem.

3.3.2 Infixation and Root and Pattern Morphology

In section 1.1.8 we noted the Silt'i data repeated here from (10):[7]

We noted that such Semitic languages have roots composed of three consonants, as exemplified in the Silt'i data in (121), where ‘buy’ is the root wkb. The aspect markers are composed of vowel patterns that fit between or around the root consonants, such as the a-a vowel pattern indicating the perfective aspect shown in (121).

How does one model this in Stage 1 of FieldWorks Language Explorer? (See B.1.1.2.1 for how to write an affix process for this using the new experimental phonological rule-based parser.)The basic idea is to treat each vowel as an infix.

3.4 Epenthesis

In section 1.1.4 we noted the Caquinte data repeated here from (6).[6]

Recall that this is an instance of epenthesis. Many languages have certain syllable well-formedness constraints that require the insertion of either a vowel or a consonant to preserve syllable structure (see Itô 1989 for an interesting discussion). In the data above it is a consonant t.

How can one model such epenthetic segments within Stage 1 of FieldWorks Language Explorer? There are at least two ways:

The advisability of the use of the first method is debatable. If the epenthetic segment is rather common, then one might want to model it as a pseudo-morpheme. Such an approach allows you to use the output of FieldWorks Language Explorer to explore where it occurs and perhaps glean some insights about its true nature. The second approach captures the fact that epenthesis has no meaning whatsoever (as one would expect with a true morpheme) but it misses the generalization that the presence of the segment is due to syllabification considerations (by adding otherwise unnecessary allomorphs to many dictionary entries). Stage 1 of FieldWorks Language Explorer does not model syllables.

3.5 Metathesis

Another morphophonemic issue we noted in section 1.1 was metathesis. We repeat the Caquinte word in (11) given in section 1.1.9.

Recall that the h and a in the final two morphemes switch positions.

How does one model such metathesis processes in Stage 1 of FieldWorks Language Explorer? Since Stage 1 does not have any way to model processes, one must use allomorphy. For data like that in Caquinte, one would

3.6 Morphemes that May Be Null

Recall that in section 1.1.10 we noted some other Caquinte data in (12) repeated here (you do not need to understand all the morpheme glosses here; just concentrate on the initial subject prefixes):

What is the issue with the subject prefixes? In (129a) we see that the first person inclusive subject marker is a‑, and in (129b) the third person feminine subject marker is o‑. Yet, in (129c), the gloss shows ambiguity between ‘we’ and ‘she’ as the subject, and both of these are represented as null. This is because both subject prefixes are vowels and the stem in (129c) is vowel-initial, yielding two vowels together. Recall from (125) that Caquinte generally does not allow vowel clusters, and therefore adds an epenthetic ‑t‑ when necessary to avoid such clusters. It turns out that epenthesis is only used in the suffixes. Within the prefixes, the initial vowel of a cluster deletes, causing the ambiguity seen in (129c).

How does one model such allomorphy in Stage 1 of FieldWorks Language Explorer?

3.7 Non-phonologically Conditioned Allomorphy

Sometimes there is unpredictable allomorphy in either stems or in affixes. How does one deal with these? We have already seen how to deal with affix allomorphy determined by inflection classes in section 2.1.2.6. The following two subsections explain how to use morpho-syntactic features to control both stem allomorphy and affix allomorphy.

3.7.1 Stem Allomorphs Conditioned by Morpho-syntactic Features

The next morphophonemic issue we address relates to dealing with various inflectional stems which can appear in word paradigms. For example, consider the following data from Orizaba Nahuatl.[53]

Notice the shape of the root. It is neki in present tense, but merely nek in the past tense. A more complete look at the rest of the verbal paradigm would show that the shorter nek form also occurs with the pluperfect, the durative, and some special aspectuals. The longer neki form occurs everywhere else in the verbal paradigm.[54]

Further note that this truncation of the final vowel does not appear to be phonologically conditioned. Rather, it is conditioned by the inflectional features of the word itself. If the word is in past tense (or is pluperfect or is durative or has one of the special aspectuals), then the truncated allomorph of the root is used. Otherwise, the longer form of the root is used.

So what we would need is “something” that allows us to define the sets of inflection features that must be present in order for a particular stem allomorph to be licit. We would then associate that particular stem allomorph with that “something” so that we and the parser both know that the allomorph can only occur when one of those feature sets is present. Further, since we are talking about inflection features, this “something” should be associated with the appropriate category which can inflect for the features contained in these sets. In the Nahuatl case, this would be the verb category.

So what is this “something” in FieldWorks Language Explorer? It is what we call Stem Names. Each Stem Name is defined in a particular category. Each Stem Name has one or more sets of inflection features associated with it. Whenever a stem allomorph is tagged with such a Stem Name, then the FieldWorks Language Explorer parser will only allow that allomorph to be valid if one of the sets of inflection features is present.

For example, for the Nahuatl case in (131), we could define a Stem Name of, say, Truncates and then make at least one feature set. But how many feature sets would we need? Remember that the truncated allomorph occurs whenever the word is past tense, pluperfect, durative, or has one of the special aspectuals. Suppose we made one feature set and put all four of these features in it. This would mean that the truncated allomorph would only be valid when the word had all four features. But that never happens because some of these features are mutually exclusive. This means we would need as many feature sets as there are mutually exclusive features. In this Nahuatl case, we would need to give it four feature sets, one each for the past tense, pluperfect, durative, and the special aspectuals. Then in the lexical entry for neki we would add an allomorph of nek and tag it as belonging to the Stem Name Truncates.

In this example, what should we do with the neki allomorph? We have tagged the nek allomorph with the Truncates Stem Name so we do not need to do anything to tag the neki allomorph. The FieldWorks Language Explorer parser will automatically constrain the neki allomorph so that it will not occur with any of the inflection features defined in the Truncates Stem Name. Similarly, if a lexical entry has three allomorphs, two of which need to be tagged with distinct Stem Names, then the third, untagged, one will automatically be constrained to never occur with any of the feature sets defined for the other two Stem Names associated with the other two allomorphs in that entry.

How does one create and use a Stem Name in FieldWorks Language Explorer?

To summarize, one should use Stem Names to control stem allomorphy that is dependent not on phonological issues, but on the presence of certain inflection features. Note that Stem Names can only be used for stem allomorphs (not affix allomorphs).

Finally, note that derivational affixes may also be constrained to only occur with a particular Stem Name.[56]

3.7.2 Affix Allomorphs Conditioned by Morpho-syntactic Features

In section 3.7.1 we discuss how to control stem allomorphy based on sets of morpho-syntactic (inflection) features.[57] This section deals with something similar, but for affixes, not for stems. For example, consider the following data from Axininca Campa.[58]

Notice that in (133), the non-future suffix is ‑i except when it comes before the first person object marker ‑na where the non-future is ‑a (133a). Example (134) shows that when the non-future follows the perfect suffix, it is ‑i even when it comes before the first person object (134a).

How does one model such allomorphy in Stage 1 of FieldWorks Language Explorer? Since only allomorphy is available, one must create allomorphs for both forms of the non-future suffix and condition them to co-occur with the appropriate set of features.[59]

For the Axininca Campa data above, the verbal inflection features are for perfect aspect and for first person object agreement. We would need to create the appropriate inflectional suffixes and assign perfect aspect to the perfect ‑ak suffix and first person object agreement to the first person object ‑na suffix. For the non-future suffix, we would make the Lexeme Form be ‑i and we would create an Allomorph Form of ‑a. We would set the “Required Features” field of the ‑a allomorph to be for first person object agreement. One implication of this is that the default form ‑i of the Lexeme Form will automatically be conditioned to not occur when the first person object agreement feature is present. This means that a form like (134a) will fail to analyze correctly. Currently, a way to compensate for this is to add another Allomorph Form for ‑i, setting its “Required Features” field to be for both first person object agreement and perfect aspect.[60]

While this example is for inflectional affixes, Stage 1 of the FieldWorks Language Explorer parser also allows constraining allomorphs of derivational affixes. The process is similar: create the allomorph and constrain it via the “Required Features” field.

3.8 Irregularly Inflected Forms

Next consider the following small set of data for Turka, a language spoken in Burkina Faso.[61]

Notice that there is not an obvious way that plurals are formed. That is, the plural forms appear to be portmanteau morphemes: a combination of the singular morpheme plus plural.

At least one way to deal with this is to create irregularly inflected form variants for each of the plural forms, tagging them as being the plural variant type, and linking them to their respective singular form. If you make sure that the plural variant type[62] has its “Append to Gloss” field set to ‘.pl’(if you are going to use small caps) or ‘.PL’ (if you are not), then the FieldWorks Language Explorer parser will parse these plural variant forms, using the gloss of the singular form plus what is in the “Append to Gloss” field. When you use this method, the irregularly inflected form must have no sense information or it will not work as intended.

You can also set the “Inflection Features” field of the irregularly inflected variant type to those inflection features borne by the variant. The FieldWorks Language Explorer parser will then prevent parses where the indicated inflection features conflict with similar inflection features of other affixes that have different values.

Suppose, now, that there are some inflectional templates that have required slots and that the irregularly inflected form portmanteau morpheme has in it the information needed to fill one or more of those required slots. What will happen? Since the FieldWorks Language Explorer parser requires these slots to be filled, the parse will fail when it should not.

The solution is to set the “Slots” field of the irregularly inflected variant type to refer to all required slots in templates that it is taking the place of. The FieldWorks Language Explorer parser will then correctly parse such forms.[63] In addition, it will prevent parses where the indicated slots are filled by some other affix.

3.9 Coalescence

Another morphophonemic phenomenon can be illustrated by the following data from Menya. [64]

In example (137), the root is ma, but when this vowel-final root is followed by a vowel initial suffix as in (137b), the two vowels coalesce so it surfaces as me. In this case, the coalesced vowel also changes quality. A similar coalescence occurs in (138b) for the vowel-final root ikä.

How does one model such allomorphy in Stage 1 of FieldWorks Language Explorer? Since only allomorphy is available, one must create allomorphs for both the root and the suffixes and condition them to have the correct environments.[65]

3.10 Ad hoc Allomorph-oriented Rules

When one uses a morphological parser, it is not unusual for the parser to sometimes return a parse that is simply incorrect. These are sometimes due to allomorphs matching in places one would not have expected them to match. When one has used all the mechanisms provided by the parser to the best of one's ability and such incorrect parses continue to surface, one may well wish for some kind of mechanism to rule them out. FieldWorks Language Explorer provides “Ad hoc Rules” for such situations. Note that it may well be the case that later stages of FieldWorks Language Explorer will provide more well-motivated means to rule out these infelicitous parses, but for now, these ad hoc solutions may have to do.

3.10.1 Creating Ad hoc Allomorph-oriented Rules

There are two main types of ad hoc rules: morpheme-oriented ones and allomorph-oriented ones. This section deals with allomorph-oriented ones (see section 2.4 for morpheme-oriented ones). The basic idea is to list a key allomorph and then to list one or more other allomorphs that cannot co-occur with the key one. One can constrain these other allomorphs to never occur in one of the following ways with respect to the key allomorph:

Note that when there are two or more allomorphs listed for “other allomorphs,” the rule only applies when all of them co-occur in the same word with the key allomorph. In addition, their relative order is significant. They should be listed in the same linear order they occur in a word.

The English plurals in (141) show some cases where we might choose to use an allomorph ad hoc rule for Stage 1 of FieldWorks Language Explorer.[66]

The exceptional case, of course, is the ‑en allomorph (there are other exceptional plurals in English, but this one will do for our example here). Suppose you have these allomorphs in your dictionary and that you also have the noun molt as well as the verb molt in your dictionary. Then the word form molten would be parsed at least two ways as shown in (142).

The parse in (142b), of course, is incorrect. To rule out this incorrect parse, one could create an allomorph ad hoc rule for the en allomorph of the plural with the molt allomorph of the noun molt.

How does one create an allomorph-oriented ad hoc rule in FieldWorks Language Explorer?

By the way, when you are indicating the allomorph, be sure that the particular allomorph is for the correct morpheme, too. FieldWorks Language Explorer maintains a distinction between identically shaped allomorphs; only those for the particular morpheme will actually be constrained.

3.10.2 Grouping Ad hoc Allomorph Rules

Occasionally one finds a situation where a set of ad hoc constraints have a common theme. Perhaps they all relate to a particular allomorph or to particular allomorphs of a certain variety. This may be a hint as to what is really happening and may lead you to discover a linguistically-motivated way to model them. Or it could be that the FieldWorks Language Explorer model just does not happen to provide the appropriate linguistic mechanism to model the phenomenon correctly.

One can group such ad hoc rules together. How does one create such a group?

Finally, note that FieldWorks Language Explorer allows one to group both allomorph and morpheme ad hoc rules together. Please be sure to only do so if these rules truly do have something in common.

4 Lexical Entry Considerations

This section lists a few items that one should keep in mind while adding lexical entries.

4.1 Allomorphs

There are two things to keep in mind while keying Lexeme Forms and Allomorph Forms.

4.1.1 Null Allomorphs

Generally speaking, one wants to avoid having null allomorphs if for no other reason than that they can make the parser run rather slowly. If having a null allomorph is indeed the best analysis, then please keep the following in mind:

4.1.2 Order of Allomorphs within a Lexical Entry

In Stage 1 of FieldWorks Language Explorer, the order of Lexeme Forms and Allomorph Forms is quite significant. Consider the following English data.

Under one possible analysis, we can say that the allomorphs for the English plural are:

1. ‑ιz after strident segments
2. ‑z after voiced (but non-strident) segments
3. ‑s elsewhere

If we have a natural class for stridents and one for voiced segments (including stridents) and create two environments (one for “after stridents” and one for “after voiced segments”), then we can order and condition the allomorphs as follows:

1. ιz to occur after stridents
2. z to occur after voiced segments
3. s

Because of the ordering and the fact that the first two are conditioned, the third (elsewhere) case will automatically be constrained to not occur after stridents as well as to not occur after voiced segments. The second allomorph will be conditioned to not only occur after voiced segments, but also to not occur after stridents.

Do you see how it works? For a given Allomorph Form, FieldWorks Language Explorer applies the condition of this Allomorph Form and, at the same time, negates the conditions of all preceding Allomorph Forms. This is why the ordering of allomorphs is crucial.

Having said that, please note that the Lexeme Form field is always automatically ordered last after all of the Allomorph Forms listed in the Allomorphs section of Lexicon Edit.

4.2 Morpheme Types

Morpheme types are things like “root,” “prefix,” “clitic,” etc. Stage 1 of FieldWorks Language Explorer keys on certain ones of these in order to tell the parser how to handle the particular form. The types in the following list are significant to the parser.[69]