Defining Inflection Rules for a Lexical Type

For inflected forms of lexical items to be automatically recognized within personal examples, inflection rules must exist for the appropriate lexical types. Inflection rules are used instead of conjugations when lexical items inflect in simple or predictable ways such that the inflected forms are not worth entering into a lexicon. An obvious example is the inflection of English nouns to form the plural. An English student wants plural forms of nouns to be underlined automatically when he uses them in personal examples. The same is true for a Spanish student who writes some personal examples for adjectives. It shouldn't matter if she uses the plural form of an adjective or changes the gender of an adjective. In both scenarios, the students don't want to have to manually underline inflected forms of lexical items an every personal example that uses them. By defining inflection rules you can have the program do it for you.

As is the case with conjugations, inflection rules are defined on the Inflection tab of the New Lexical Type dialog or the Lexical Type Details dialog (both dialogs are virtually the same). On this tab, select Inflection Rules from the dropdown. The will cause the rule table to be displayed underneath the dropdown, which contains at least 5 columns: Group, Affix Type, Affix, Operation, and New Affix. If any genders or lexical classes exist for the lexical type then a Gender and Class column will also be present. Each row in the table represents one inflection rule. You can add a rule with the Add button and delete a rule by selecting it and clicking the Remove button. Also, you can adjust the order of the rules by selecting one and clicking the up and down arrow buttons. As we'll see, rule order is important.

The first thing to understand about inflection rules is that they're almost never perfect. Languages can behave inconsistently and often import words from other languages. Both of these factors mean that, while you can usually come up with generic rules to cover 95% of lexical items, there will still be 5% that don't conform to any rule. Any program that recognizes all inflected forms of all words would require it's own dictionary for the relevant language. The purpose of Personal Lexicon is not to provide you a ready-made dictionary as much as it is to help you build your own. Having said that, almost all languages define sets of rules that govern most of the inflection found in the language. If you study the language closely (or consult your textbook or the Internet), you'll be able to construct a solid set of inflection rules for your lexicon. And when you happen to use an unrecognized inflected form in a personal example then you can always underline it manually using the F1 key.

Inflection rules are applied in groups. When a lexical item is assigned a lexical type that defines inflection rules then the program takes the first rule group and tries to apply each rule in the group to the item. A rule match is found if 1) its gender is the same as the lexical item's gender, 2) its class is also the same, and 3) its affix text matches either the beginning or ending of the item text depending on the affix type defined by the rule. An affix is either a prefix or a suffix. When the rule defines the affix type to be prefix then the item text must start with the rule's affix text in order for a match to occur. Conversely, the item text must end with the rule's affix text if the affix type is set to suffix.

Using English nouns as an example, plural inflection always begins by examining a word's suffix. Most nouns are made plural with the addition of an s, but words that end with ch, s, sh, x, or z are made plural with es. Some other words change y to ies. Of course, English nouns don't have either gender or class, therefore a word's suffix is the only factor to consider when applying plural inflection rules. When a rule match occurs, the last two table columns determine how the inflection is done. The Operation column indicates if the item text should be added to or changed. Whether text is added or changed at the beginning or end of the item text depends on the affix type. The New Affix column specifies the text that is added to the item text or that replaces the original affix text found in the item text.

Sometimes it's useful for an inflection rule to apply to more than one affix. As we've already mentioned, English nouns that end with ch, s, sh, x, or z are made plural by adding an es. You could make five separate inflection rules to accommodate each suffix, but it's a better idea to combine the suffixes into one rule since the new suffix, es, is the same. To do this, simply place a comma between the different affixes. The following table shows the noun inflection rules that we have discusses so far, plus an addition rule for words that end with a vowel followed by y:

Group

Affix Type

Affix

Operation

New Affix

plural

suffix

ch,s,sh,x,z

add

es

plural

suffix

ay,ey,oy,uy

add

s

plural

suffix

y

change

ies

plural

suffix

 

add

s

Notice the rule order. It plays an important role in the application of inflection rules. When the program looks for an inflected form of the item text within a personal example, it scans the first rule group for a rule that matches the lexical item in question. If a rule is found then any remaining rules within the group are skipped. In our example, only after no match is found with the first 3 rules does the final rule kick in. Because its suffix is blank, this rule will apply to any lexical item.

Let's take a look at a couple specific cases. For the lexical item ostrich, an match occurs with the first rule because the word ostrich ends with ch. Therefore, the word ostriches will be underlined automatically in a personal example that uses it. "Ostrichs" won't be recognized because, even though the last rule would have applied, an applicable rule was found before it got there. However, in the case of bathtub, none of the rules match until the last one. This means bathtubs will be underlined, but not "bathtubes" or "bathtubies".

Sometimes there may be a need to define multiple rule groups when lexical items have more than one valid inflected form or when the language isn't consistent. Returning to our example of English nouns, when a noun in the singular ends with f or fe then typically this suffix changes to ves to form the plural (e.g. wolf changes to wolves and wife changes to wives). However, a few words end with f that simply take an s to form the plural (e.g. roof changes to roofs). In this case, we could put the first f,fe rule in our main plural group and then add another rule to a second group that we name alt plural.

Group

Affix Type

Affix

Operation

New Affix

plural

suffix

ch,s,sh,x,z

add

es

plural

suffix

ay,ey,oy,uy

add

s

plural

suffix

y

change

ies

plural

suffix

f,fe

change

ves

plural

suffix

 

add

s

alt plural

suffix

f

add

s

Now, a lexical item that ends in f will have two recognized inflected forms. Both words, wolves and roofs will be underlined. However, if you mistakenly use "wolfs" or "rooves" in a personal example then these forms will also be underlined. Unfortunately, this is one of those cases when inflection rules don't work perfectly. As long as you enter the correct plural form, there's no problem. But if you're a language student learning English for the first time then it's quite possible you don't realize that most words ending in f change to ves to form the plural or that roof is an exception to the rule. It would be perfectly understandable if you used "wolfs" instead of wolves. This is another reason why having your personal example verified by your teacher is such a good idea. Plus, you might have made other grammar errors that should be corrected.

A rule group can be named anything you want. If you decide to create a new group then just type the name into the group column of a rule. If you want to assign a rule to an existing group then you can type in the group name again or select it using the dropdown control available in the table cell. Rules that aren't assigned a group name (i.e. the group name is blank) are put into a default group. In our last example, the alt plural group was created because the last rule in the plural group would never be applied to words that end with f. Roofs wouldn't be a recognized because the f,fe rule would have matched before the final rule in the plural group. Therefore, we needed to create another rule in a separate group that allowed for a second match to occur.

However, sometimes it's preferable that all rules in a group get applied to a single lexical item. This is useful for lexical types that define multiple inflected forms for each lexical item. If all rules of a particular group define the same matching conditions then the program assumes that lexical items of this type can take on all the inflection forms. In other words, if all rules define the same gender, class, affix type, and affix then a lexical item that matches these constraints will have all rules applied to it. For example, a German adjective can inflect in many ways depending on how it's used in a sentence (i.e. gender, number, and case) and whether the speaker wants to use the positive, comparative, or superlative form. The following is a subset of inflection rules for German adjectives:

Group

Affix Type

Affix

Operation

New Affix

Formen Positiv

suffix

 

add

e

Formen Positiv

suffix

 

add

em

Formen Positiv

suffix

 

add

en

Formen Positiv

suffix

 

add

er

Formen Positiv

suffix

 

add

es

Notice that the Affix column is blank, meaning there are no constraints on which lexical items these rules apply to. Moreover, because all the rules in the group are defined with the same constraints (i.e. all rules define no constraints) then all rules will be applied to any lexical item that is an adjective. Therefore, valid forms of the German adjective hoch, meaning tall, will include hoche, hochem, hochen, hocher, hoches, etc.