Story grammars - Narrative Intelligence - page 204

STORY

SETING EPISODE+

EPISODE EPISODE

EVENT EMOTION ACTION OUTCOME

occurs(Event,Time)

Figure 1. A partial parse tree for a simple narrative showing a leaf template.

The second argument of the episodes rule is the temporal interval over which
all the episodes in the list take place. The temporal constraints in the episodes
rule capture the relations among the intervals associated with the first episode,
the remaining episodes, and the overall episodes list. The episode rule describes
the relations among an episode's four components and the associated temporal
intervals.
The left hand sides of most rules specify other components which the right
hand side relates to the non-terminal defined by the rule. This allows the gram-
mar to capture constraints within the rule itself rather than as a “semantic an-
notation.” By adding arguments to the non-terminals in the rules, the grammar
achieves the expressive power of a Type 0 grammar, as Black and Wilensky con-
clude a story grammar must (Black and Wilensky 1979). Below are two rewrite
rules from the grammar for stories.

episodes(episodes([ep(Ev, ER, A, O)|Es]), int(Start, End)) ->
episode(ep(Ev, ER, A, O), P, int(Start, Mid)),
episode_rec(Es, P, int(Mid, End)).
episode(ep(ev(Ev, Ev_time), emot(Em, Resp_time)), A, O), Ep_time) ->
story_event(Ev, Ev_time),
wm_call([emot_reaction, Ev, Em]),
emot_response(Ev, Em, Ev_time, Resp_time),
wm_call([act_motiv, Em, A]),
action_response(A, O, Act_time, Outcm_time),
{starts(Ev_time, Ep_time),
finishes(Outcm_time, Ep_time),