Irregular forms

The rules in the morphology table thus permit the redundancy of systematic inflectional suffixes to be removed from individual lexical entries. GWB also allows redundancies to be factored out of irregular inflections, forms whose morphographemic variations do not conform to any of the common patterns. For example, the verb go has irregular past tense and past participle forms (went and gone). The inflectional features of these forms cannot be supplied by general rules, but they do share root features with go and with the more regular

third-person singular goes and present participle going. All forms of go have at least the same PRED semantic form and perhaps other features as well.

Schemata can be shared among the various forms of a word by placing them in a separate, distinct lexical entry under a special morphcode ROOT. You can enter the root schemata common to the various forms of go can be entered in the lexicon under the stem go-:

go- V ROOT (↑ PRED)=’GO<(↑ SUBJ)>’.

This is in some sense a pseudo-lexical entry, much like the entries for the various affix schemata, since the heading of the entry is not something that is expected to appear by itself in a sentence. Spelling the heading with a hyphen at the end is a useful convention for marking this fact and also for indicating that these are features for a root that is to be completed by the addition of features typically associated with some suffix.

The individual forms of go can then refer to these root features by specifying go- in a special morphcode format. The entries for gone, for example, can be entered as

gone V @go- (↑ PARTICIPLE)=PAST.

The @ in the morphcode indicates that gone is a verb whose schemata are the result of conjoining the V-ROOT schemata of go- with the idiosyncratic participle schema for this inflectional form. The past-tense form can be defined in a similar manner:

went V @go- (↑ TENSE)=PAST.

The infinitive and third-singular forms could also be defined in this way, with their inflectional schemata listed explicitly. But these schemata are not idiosyncratic at all—they are identical to the schemata of the normal inflectional affixes -VINF and -V3SG that were defined above. This commonality can be represented by including the names of the inflectional affixes in the @ morphcode without listing any additional distinctive schemata:

go V @(go- -VINF). goes V @(go- -V3SG).

The parenthetic morphcode permits the morphological analysis of these words to be given explicitly, indicating that their schemata come from the go- root and the normal inflectional affixes.

Entries of this type can be used to relate all the forms of a given stem to common lexical material defined in a special stem entry, conventionally spelled with a trailing hyphen, and to the schemata associated with independently specified inflectional affixes. Each of the forms requires a separate lexical entry, and clearly this cannot be avoided for a verb like be that has completely idiosyncratic inflectional realizations. But many stems have only a few forms that do not conform to a regular paradigm. In English, for example, the third-person singular and present-participle forms are almost always regular; only the past and past participles show idiosyncratic variation. The morphtable mechanism can be used to express this sort of subregularity and thus avoid the need for explicit specification of forms like goes and going (and also the citation form go, given that it is related to the stem go- in a conventionally systematic way). This is accomplished by providing a more discriminating morphcode in the stem and also morphtable entries to interpret the subregularity represented by that morphcode. Thus, the fact that go and do take the standard -es and -ing suffixes can be indicated by changing the ROOT morphcode in their stem entries to a new code ES-ING:

go- V ES-ING (↑ PRED)=’GO<(↑ SUBJ)>’.

4. Morphology

The interpretation of this morphcode is then provided by additional morphtable entries: (es - (V ES-ING -V3SG))

(ing - (V ES-ING -VING)) ("" - (V ES-ING -VINF))

The first line allows the es suffixes in goes and does to be replaced with hyphens to produce the stem forms go- and do-. Since these are marked with the morphcode called for in the table entry, this analysis results in the appropriate third-singular schemata. The second entry identifies going and doing as the present participles of go- and do-, respectively, and the third line accounts for the base forms go and do. Rules such as these make it unnecessary to have separate entries for regular forms of irregular verbs. Only the stem and its truly irregular variants must be specified. The truly irregular forms are defined just as before:

gone V @go- (↑ PARTICIPLE)=PAST. went V @go- (↑ TENSE)=PAST.

When a ROOT morphcode is not present in the stem entry to identify the intended root schemata, the system extracts the schemata associated with any single morphcode for the indicated category that does exist in the root entry (ES-ING in the go- example).

This mechanism for expressing subregularities can be used even when an irregular form has the same shape as a separate regular form, as is the case for the past and past-participle forms of hit. The infinitive can be derived from the stem hit- by virtue of a morphtable entry for the subregular gemination morphcode S-#ING:

(#ing - (V S-#ING -VING))

But hit would also have its own lexical entry, providing explicitly only for the past/past-participle inflection:

hit- V S-#ING (↑ PRED)=’HIT<(↑ SUBJ)(↑ OBJ)>’. hit V @(hit- -VPAST).

The result of the morphtable analysis will be taken as an alternative to the explicit entry to provide an ambiguous representation for hit.

The several ways of specifying the morphological decomposition of a single word can be combined to characterize complex homophonous forms. The word saw, for example, can be a verb in two senses, either as the irregular past of see or the regular root of saw. It can also be a common noun. All these possibilities are expressed in the following lexical entries:

saw V {@see- (↑ TENSE)=PAST;

S-ED (↑ PRED)=’SAW-WOOD<(↑ SUBJ)(↑ OBJ)>’} N S (↑ PRED)=’SAW’.

see- V ROOT (↑ PRED)=’SEE<(↑ SUBJ)(↑ OBJ)>’.

These entries illustrate how curly-brackets with a semicolon separator can be used to represent alternative morphcode-schemata combinations.

As you can see, the combination of ROOT and @ references can define complicated dependencies between the definitions of various items. The Find Root item in the Lexicon window menu helps you keep track of those dependencies.