Comparison variables
From OpenCog
RelEx attempts to generate relations that indicate comparatives. However, support for comparatives is currently very incomplete; essentially only one sentence type is supported.
Consider the two sentences: "Ben ate more cookies than Mike." and "Ben ate more cookies than Twinkies." These sentences are ambiguous because it is not clear if Mike/Twinkies is a subject (who is eating) or an object (and is being eaten). This ambiguity is captured in the parse:
_subj(eat, Ben) _obj(eat, cookie) more(cookie, _$cVar) _$crVar(_$cVar, Mike)
_$cVar is the comparative variable, and _$crVar is the comparative relation variable. For this example, _$crVar can be _subj or _obj, while _$cVar is "eat"
Thus, there are two possibilities:
_$crVar(_$cVar, Mike) ==> _subj(eat, Mike) more(cookie, _$cVar) ==> more(cookie, eat)
implying that Mike eats cookies.
_$crVar(_$cVar, Twinkies) ==> _obj(eat, Twinkies) more(cookie, _$cVar) ==> more(cookie, eat)
implying more Twinkies are being eaten.
By contrast, not all sentences are ambiguous: "Ben ate more cookies than Mike did." makes it clear that "Mike" is a subject, doing eating, and cannot be the object being eaten.
