The Taming of Converse: Reasoning about Two-way Computations
نویسنده
چکیده
We consider variants o f propositional dynamic logic (PDL) augmented with the converse construct. Intuitively, the converse a of a program a is a programs whose semantics is to run a backwards. While PDL consists o f assertions about weakest preconditions, the converse construct enable us to make assertions about strongest postconditions. We investigate the interaction of converse with two constructs that deal with infinite computations: loop and repeat. We show that converse-loop-PDL is decidable in exponential time, and converse-repeat-PDL is decidablc in nondeterministic exponential time.
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