Lexical entries are introduced using the infix operator -->/2. The syntax of a lexical entry is as follows:
<lexical-entry> ::= <entry>
| <morph-rule>
<entry> ::= <lexical-item> ---> <tecto-category>
<morph-rule> ::= (<entry>) :- <prolog-goals>
<lexical-item> ::= <prolog-atom>
| <prolog-variable>
A <lexical-item> should be either a Prolog atom or variable. A <tecto-category> is either a description or variable. An <entry> can be placed in the head of a Prolog conditional clause to define morphological processes. The following examples of lexical entries are from the file german.pl:
will ---> (aux,form:inf). (sieht ---> (tv,person:third,number:sg,form:pres)):- !.
For more examples, refer to the files german.pl and sc.pl.
Because the lexicon as defined here is not static and may encode morphological processes, it is an unreliable source of information for inducing lexical categories. TGC, therefore, uses the tecto-rules for this purpose. Any category is considered lexical if no category corresponding to that category appears in the left-hand side of the tecto-rules. In the following example, Aux, Pron and TV are thus considered lexical:
s *--> [(np, person:P, number,N, case:nom),
(vp, person:P, number:N)].
s *--> [(np, person:P, number:N, case:nom),
(aux, person:P, number:N, form:F),
(vp, person:no,number:no,form:F)].
(np, person:P, number:N, gender:G, case:C) *-->
[(pron, person:P, number:N, gender:G, case:C)].
(vp, person:P, number:N, form:F) *-->
[(vbar, person:P, number:N, form:F)].
(vbar, person:P, number:N, form:F) *-->
[(tv, person:P, number:N, form:F),
(np, case:acc)].