© 1986 by British Computer Society
| ||||||||||||||||||||||||||||||||||||||||||||||||||||
A Structure-directed Total Correctness Proof Rule for Recursive Procedure Calls
Computer Science Group, Tata Institute of Fundamental Research, Homi Bhabha Road, Bombay 400 005, India
Recursive procedures have been extensively used for a long time, yet it was only in 1977 that Sokolowski gave a proof rule for the total correctness of recursive procedure calls. Unfortunately, even for simple programs his rule requires the use of complex predicates that encode information about the depth of recursion. Thus the rule can be very difficult to use for practical programs. In this paper we propose a new rule for this purpose. This rule makes use of the structure of the recursion which is discovered by carrying out an interval analysis of the procedure call graph in the proof. Proofs using this rule are simpler to carry out, and it is shown that Sokolowski's rule is in fact a special case of the new rule.
Received March 1985.
* To whom correspondence should be addressed.
Computer Science Group, Tata Institute of Fundamental Research, Homi Bhabha Road, Bombay 400 005, India