Story grammars - Narrative Intelligence - page 210

issue of coherence by incorporating explanation closure (Shubert 1990) into
the search strategy (Stewart & Lang 1998; Gardere 2000).
The model, as presently implemented, captures various kinds of non-
stories as well as the ethnic narratives under consideration. Some stories jux-
tapose characters in a way that conforms to common-sense notions associ-
ated with those characters (maidens are innocent, wolves are fierce and cruel,
etc.); other stories place characters in counterintuitive roles. This is evidence
that the model suffers from an inadequate representation of characters. We are
presently exploring agent design models (Bailey 1999; Meech 1999; Frank &
Stern 1998; Sengers 1998).
Our approach depends heavily on the world model and suffers from the
problems that many knowledge-based systems share. The present implemen-
tation enumerates, prior to generation, the actions, goals, effects, etc. that may
appear in a story. The present implementation is ontologically promiscuous in
this regard. Furthermore, although the world model predicates have access to
all states and events reported in a story up to the point the world model pred-
icate is triggered, the implementation does not consider unreported states or
events entailed by those that are reported.
Despite these shortcomings, the Joseph story generation system represents
a significant achievement since it is the first such system constructed from an
explicit, formal model for stories. The Joseph system constructively demon-
strates the value of the insights and intuitions put forth by the proponents of
story grammars in the 1970s and early 80s. Lakoff, Colby, Rumelhart, Mandler
and Johnson, Stein and Glenn, Bower, Thorndyke, and Frisch and Perlis were
correct to assert that formal grammars can be utilized to describe the features of
narratives. Although Joseph's domain is ethnic folktales, the approach applies
to stories in general. For example, initial efforts have been made to use this ap-
proach to generate algebra word problems (Matthews 1999; Thompson 2000).
The viability of story grammars is good news since formal grammars are well-
analyzed and well-understood tools for describing classes of structured objects
such as narratives.
References
Afanasev, Aleksandr. N. (1974). Russian folk tales .NewYork:E.P.Dutton.
Afanasev, Aleksandr. N. (1975). Russian fairy tales .NewYork:PantheonBooks.
Allen, James F. (1984). Towards a general theory of action and time. Artificial Intelligence , 23
(2), 123-154.