In this paper we describe an improved formalisation of slicing in WSL transformation theory and apply the result to a particularly challenging slicing problem: the SCAM mug [1]. We present both syntactic and semantic slices of the mug program and give semantic slices for various generalisations of the program. Although there is no algorithm for constructing a minimal syntactic slice, we show that it is possible, in the WSL language, to derive a minimal semantic slice for any program and any slicing criteria.
Martin P. Ward