We study programs that perform I/O and finite or countable nondeterministic choice, up to finite trace equivalence. For well-founded programs, we characterize which strategies (sets of traces) are definable, and axiomatize trace equivalence by means of commutativity between I/O and nondeterminism. This gives the set of strategies as an initial algebra for a polynomial endofunctor on semilattices. The strategies corresponding to non-well-founded programs constitute a final coalgebra for this functor.
|Number of pages||22|
|Journal||Electronic Notes in Theoretical Computer Science|
|Publication status||Published - 11 Dec 2018|