Bad Variables Under Control

Andrzej S. Murawski

Abstract: We give a fully abstract game model for Idealized Algol with non-local control flow. In contrast to most previous papers on game semantics, we do not need to include the bad-variable constructor mkvar to obtain full abstraction. Using the model we show that, unlike in the “control-free” case, the presence of mkvar does affect observational equivalence. We conclude by discussing the effect of mkvar on nondeterministic and probabilistic variants of Idealized Algol.