A HYBRID MODEL OF REASONING BY ANALOGY

Evaluation can be started after the transfer of new knowledge is finished, but it is also possible to
evaluate each single transfer (before the transfer process proceeds). As Keane (1988) points out,
usually in a familiar target domain the evaluation is done during transfer, while in unfamiliar
domains often a hypothesis needs to be tested in the real world after the transfer is complete.
Learning is running in parallel to all other processes, enabling the storing of maps, analogical
inferences, evaluations or failures, and all other kinds of intermediate results. It can, however, start
after the problem is solved as well, in order to store the target description together with the
solution, possibly to make some generalizations and store them, and to adjust link weights in order
to provide for better retrieval in the future.
All triggering of these symbolic processes as well as their termination and speed are controlled by
the associative mechanism, i.e. by pragmatic factors.
6. A COMPUTER SIMULATION
A computer implementation of AMBR has been developed that simulates human problem solving
in the area of cooking and boiling water, eggs, etc. in the kitchen or in the forest. The simulation
system demonstrates AMBR's capability of analogical problem solving as well as some of the
priming effects found in the experiments described in section 2.
The Simulation Program has been developed in Common Lisp on an AT/286-type computer with 6
MB of RAM.
6.1. The Knowledge Base of the Simulation and the Target Problem
The knowledge base of the simulation program contains about 300 nodes and 4,000 links. There
are about 10 situations related to water, three of which are the following: A) heating water on the
plate of a cooking-stove in a pot (figure 11a), B) on the fire in a wooden vessel (figure 11b), and
C) heating water by means of an immersion heater in a glass (figure 11c).
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A simplified formulation of the target problem given in the psychological experiments is used as a
test example in the simulation: how can you heat water in a wooden vessel when you
are in a forest, having only a knife, a match-box and an axe. The problem is
represented in the following way: the reasoner should look for a situation in which the water is in a
wooden vessel and which will cause another situation in which the water will be hot and will still
be in the wooden vessel (figure 12).
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The links between the nodes corresponding to these situations (e.g. G1) and the nodes
corresponding to all concepts referred to in these descriptions (G101, G102, etc.) are weighted
(the weights are not shown on the figure for simplicity). There are also weighted a-links in the
reverse direction (e.g. from water to G101, and from G101 to G1). The weight of a link depends
on the typicalness of the corresponding relation, i.e. how often it is used. For example, the
weights of the links between water and heat on the one hand and situation A on the other hand are
greater then that connecting water and heat with situations B and C, because A is a more typical
situation then B and C.