We have presented a formalization
of STRIPS as a reasoning strategy
in the situation calculus.
In doing so, we have proposed and
illustrated a conceptual framework
for the declarative formalization
of reasoning strategies consisting
of mental situations, mental actions,
and heuristics. Declarative
formalizations of reasoning strategies
have a number of advantages. One of them
is that they can be improved by simple
additions of better heuristics
[17] [16].
For example, axioms 
,
and describe
the heuristics used for determining
which actions are appropriate for
achieving a subgoal, ordering actions,
and detecting dead-ends during the
searching process. We can enhance the
reasoning strategy formalized in the
paper by simply adding new disjuncts
describing better heuristics to the
right hand side of any of those axioms.
The author would like to thank John McCarthy for introducing her into the idea of the mental situation calculus, suggesting the problem of the declarative formalization of reasoning strategies, and providing valuable ideas, comments and help whenever they were needed. Luc Steels encouraged and enriched the writing of this paper with valuable ideas. Mike Genesereth read carefully a previous version of the paper, and contributed with valuable comments. John McCarthy, Tom Costello, Eyal Amir and Aarati Parmar participate in useful discussions that helped to shape the final version of the paper. This work was supported partly by the Navy Grant N00014-94-1-0775, and partly by the Air Force Grant F49620-97-1-0207.