Slicing the SCAM mug: a case study in semantic slicing

We describe an improved formalisation of slicing in WSL transformation theory and apply the result to a particularly challenging slicing problem: the SCAM mug (Anon, 2001). 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.