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Summary: Reasoning about Abstract State Machines:
The WAM Case Study
Gerhard Schellhorn
Abt. Programmiermethodik,
Universitat Ulm, 89069 Ulm, Germany
schellhorn@informatik.uni-ulm.de
Wolfgang Ahrendt
Institut fur Logik, Komplexitat und Deduktionssysteme
Universitat Karlsruhe, 76128 Karlsruhe, Germany
ahrendt@ira.uka.de
Abstract: This paper describes the rst half of the formal veri cation of a Prolog
compiler with the KIV Karlsruhe Interactive Veri er" system. Our work is based
on BR95 , where an operational Prolog semantics is de ned using the formalism of
Gurevich Abstract State Machines, and then re ned in several steps to the Warren
Abstract Machine WAM. We de ne a general translation of sequential Abstract State
Machines to Dynamic Logic, which formalizes correctness of such re nement steps as a
deduction problem. A proof technique for veri cation is presented, which corresponds
to the informal use of proof maps. 6 of the 12 given re nement steps were veri ed. We
found that the proof sketches given in BR95 hide a lot of implicit assumptions. We
report on our experiences in uncovering these assumptions incrementally during formal
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