4 research outputs found
Combining Semilattices and Semimodules
We describe the canonical weak distributive law of the powerset monad over
the -left-semimodule monad , for a class of semirings . We
show that the composition of with by means of such
yields almost the monad of convex subsets previously introduced by
Jacobs: the only difference consists in the absence in Jacobs's monad of the
empty convex set. We provide a handy characterisation of the canonical weak
lifting of to as well as an algebraic
theory for the resulting composed monad. Finally, we restrict the composed
monad to finitely generated convex subsets and we show that it is presented by
an algebraic theory combining semimodules and semilattices with bottom, which
are the algebras for the finite powerset monad
Combining probabilistic and non-deterministic choice via weak distributive laws
International audienceCombining probabilistic choice and non-determinism is a long standing problem in denotational semantics. From a category theory perspective, the problem stems from the absence of a distributive law of the powerset monad over the distribution monad. In this paper we prove the existence of a weak distributive law of the powerset monad over the finite distribution monad. As a consequence, we retrieve the well-known convex powerset monad as a weak lifting of the powerset monad to the category of convex algebras. We provide applications to the study of trace semantics and behavioral equivalences of systems with an interplay between probability and non-determinism