a which is defined on a triangle shown in Fig. 2. Let us try to prove the deducibility: Introduction 23 c Fig. 0. 2. cry- ( h a b ~ S), In this case, the deduction is performed through the following sequential steps: 1.

N 3 N 1411131 1211 I! /N Fig. 0. 4. where g(v) - route length from S O to S v (S v is the state corresponding to the vertex v; h(v) - estimated route length from S v to Sk; f(v) - resultant estimator. Suppose Vl,V 2..... v z - are candidates for a sequel (alternative movements of the counter in the current state). Then the vertex with minimal value of f(v) is to be chosen. Give a search algorithm using the estimator f as described in [5]. Suppose S ~ is a set of vertices already chosen, S is a set of vertices which are candidates for sequel, S ~ S ~ = a , v 0 is the initial vertex, v k is the terminal vertex in G; let G(v) denote child vertices of v, the vertices already passed being eliminated.