Given a program P , an unfold/fold program transformation system derives a sequence of programs P = P0 , P1 , : : : , Pn , such that Pi+1 is derived from Pi by application of either an unfolding or a folding step. Existing unfold/fold transformation systems for deenite logic programs diier from one another mainly in the kind of folding transformations they permit at each step. Some allow foldin...

We consider the problem of automatic precondition inference. We argue that the common notion of sufficient precondition inference (i.e., under which precondition is the program correct?) imposes too large a burden on callers, and hence it is unfit for automatic program analysis. Therefore, we define the problem of necessary precondition inference (i.e., under which precondition, if violated, wi...

We study the relationships between the correctness of logic program transformation and program termination. We consider deenite programs and we identify somèinvariants' of the program transformation process. The validity of these invariants ensures the preservation of the success set semantics, provided that the existential termination of the initial program implies the existential termination ...

We describe a simple and fast algorithm for identifying friends-of-friends clusters and prove its correctness. The algorithm avoids unnecessary expensive neighbor queries, uses minimal memory overhead, and rejects slowdown in high over-density regions. We define our algorithm formally based on pair enumeration, a problem that has been heavily studied in fast 2-point correlation codes and our re...

Given a program P , an unfold/fold program transformation system derives a sequence of programs P = P0, P1, : : : , Pn, such that Pi+1 is derived from Pi by application of either an unfolding or a folding step. Existing unfold/fold transformation systems for de nite logic programs di er from one another mainly in the kind of folding transformations they permit at each step. Some allow folding u...