A HYBRID MODEL OF REASONING BY ANALOGY

similar concepts (because they mutually activate each other through the links in LTM), and
therefore the semantic constraint prevails over the structural one and in this way the chances of a
successful mapping are lessened.
5.3. The Transfer Process
The purpose of the transfer process is to extend the mapping between two descriptions by
constructing new slots in the target description that correspond to unmapped slots in the source and
in this way to transfer new knowledge to the current situation.
Two kinds of slot transfer in AMBR will be considered in this subsection: transfer of an aspect slot
and transfer of a relation slot (action slots will not be considered for the time being). When a
relation slot is transferred, it is actually the corresponding proposition that is transferred, e.g. P(x)
or P(x1, .., xn), where P is a relation described by another description frame and x, x1, .., xn are
aspect slots with c-coref links to the descriptions of the fillers. For simplicity, only propositions of
type P(x) will be considered further; everything said about them will concern relations of arbitrary
arity as well. The following cases can be considered.
1) If, during mapping, both the aspect slot x and the relation P are mapped on x' and P'
respectively, then the slot corresponding to the proposition P(x) is easily transferred to a new slot
with a c-coref link to a description of the proposition P'(x'), i.e.
x ---> x'
P ---> P'
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P(x) ---> P'(x')
If, however, during mapping no correspondence is found for x or for P, then the reasoner is faced
with more difficult problems as discussed in 2) and 3).
2) If the object correspondence is known but the relation correspondence is unknown, i.e.
x ---> x'
P ---> ?
-----------
P(x) ---> ?
then either the same relation can be transferred: P(x) ---> P(x'), or a reinstantiation P' of some
superclass Q of P can be produced: P(x) ---> P'(x'), or the generalization Q can be used: P(x) --->
Q(x'). The particular decision would depend on the associative relevance of P, Q, and P', and on
the decisions of the evaluation process. The above is illustrated by the following examples:
water ---> coffee
container ---> cup
in ---> ?
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in(water, container) ---> in(coffee, cup)