The optimal fixedpoint of recursive programs

In this paper a new fixedpoint approach towards the semantics of recursive programs is presented. The fixedpoint defined by a recursive program under this semantics contains, in some sense, the maximal amount of “interesting” information which can be extracted from the program. This optimal fixedpoint (which always uniquely exists) may be strictly more defined than the program's least fixedpoint. We consider both the theoretical and the computational aspects of the approach, as well as some techniques for proving properties of the optimal fixedpoint of a given recursive program.