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## The Space of Mental Situations

The following axioms allow us to define precisely the space of mental situations. We use variables for blocks (x, y, z, w, ...), for situations (s, , ...), for actions (a, , ...), for mental situations (m, , ...), for mental actions ( , , ...), for formulas in the database (f, , ...), for subgoals -formulas in the goal stack- (g, , ...), for sequences of actions, (r, , ...), and for sequences of mental actions (l, , ...).

We assume uniqueness of names for every function symbol h, and every pair of distinct function symbols h and g. The symbols h and g are syntactical variables ranging over distinct function symbols; the symbols to are syntactical variables ranging over block constants. Axiom defines the expression [12], which means that mental situation can be reached from mental situation m by executing a nonempty sequence of appropriate mental actions ( is an abbreviation for ). We include domain closure axioms for blocks, mental situations, actions, and mental actions. Axiom of induction allows us to prove that a property holds for all mental situations that are reachable from a given mental situation.

Josefina Sierra
Tue Jul 21 09:26:01 PDT 1998