4.5 Coreferents


In graphical conceptual graphs, we represent that two concepts refer to the same individual by placing a dotted line between the two concepts:

Coreferents as variables

In Prolog+CG, we do this a little differently. Instead of drawing a dotted line, we simply use the same variable name as the referent of both concepts. For example:

Entity > Animal, Act.

Act = Say.

// An animal is talking to itself.
SpeechAct([Animal : A]<-AGNT-[Act : Say]-RCPT->[Animal : A]).

This example is available in the AAU directory as Aesop7.plgCG.

This graph can be drawn as follows:

Note that this can be extended to any number of concepts being coreferent. Simply use the same variable as the referent of all concepts.

Note, however, that the general scoping rules, which are explained in Part III, must be followed so that the variable names actually refer to the same variable.


In order to represent coreference links, simply use the same variable as the referent of both concepts. More than two concepts can be involved if only variable scoping rules are obeyed so that the variable name used actually refers to the same variable.

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