--15--
The restriction pattern in Fig. 2 specifies that the sen--
tence to be generated should contain a transitive verb
which belongs to either semantic class C1 or C2. The verb
should govern (I) a noun as the subject of the sentence,
(2) an object which is to be selected from the words in
semantic class C15 or the specified words W 1 and W2, and
(3) an adverb which does not belong to semantic class C19.
The subject of the sentence should not govern an adjective.
As illustrated in the pattern, each node in a pattern
contains a word class and selection restrictions which are
positively or negatively specified in terms of semantic
class(es), specific word(s) or a word class. Restriction
patterns are stored in the following form: Q-PIP2..oPn.
Q is a single pattern, or a combination of patterns, and
PIP2...P n are single restriction patterns. Essentially,
Q-PIP2...Pn is e rule which specifies that if a sentence
(or string of sentences) whose sentence skeleton(s) matches
Q, then it can be followed by a sentence whose sentence
skeleton is one of these Ps. Thus, one of these Ps is
randomly selected to be used as a restriction pattern for
a succeeding sentence. The pattern selection procedure is
not yet coded. At present, strings of restriction patterns
are given directly to the pattern selection routine. The
generation program generates strings of sentences under
the control oz direction of the restrictions specified in
the patterns. The use of restriction patterns to control
