Strong monads are important for several applications, in particular, the denotational semantics of effectful languages, where strength is needed to sequence computations that have free variables. Strength non-trivial: it can be difficult determine whether a monad has any at all, and strong multiple ways. We therefore review some most known facts about prove new ones. In we present number equiva...

We consider the problem of establishing a relationship between two interpretations of base type terms of a λc-calculus extended with algebraic operations. We show that the given relationship holds if it satisfies a set of natural conditions. We apply this result to 1) comparing two monadic semantics related by a strong monad morphism, and 2) comparing two monadic semantics of fresh name creatio...

An algebra is called corecursive if from every coalgebra a unique coalgebra-toalgebra homomorphism exists into it. We prove that free corecursive algebras are obtained as coproducts of the terminal coalgebra (considered as an algebra) and free algebras. The monad of free corecursive algebras is proved to be the free corecursive monad, where the concept of corecursive monad is a generalization o...

For a monad S on a categoryK whose Kleisli category is a quantaloid, we introduce the notion of modularity, in such a way that morphisms in the Kleisli category may be regarded as V(bi)modules (= profunctors, distributors), for some quantale V . The assignment S // V is shown to belong to a global adjunction which, in the opposite direction, associates with every (commutative, unital) quantale ...

The Dijkstra monad has been introduced recently for capturing weakest precondition computations within the context of program verification, supported by a theorem prover. Here we give a more general description of such Dijkstra monads in a categorical setting. We first elaborate the recently developed view on program semantics in terms of a triangle of computations, state transformers, and pred...

The usual monad laws can directly be used as rewrite rules for Isabelle’s simplifier to normalise monadic HOL terms and decide equivalences. In a commutative monad, however, the commutativity law is a higher-order permutative rewrite rule that makes the simplifier loop. This AFP entry implements a simproc that normalises monadic expressions in commutative monads using ordered rewriting. The sim...

We discuss conditions under which certain compactifications of topological spaces can be obtained by composing the ultrafilter space monad with suitable reflectors. In particular, we show that these inherit their categorical properties from monad. further observe various constructions such as prime open filter defined H. Simmons, closed compactification studied Bentley and Herrlich, well separa...

We show, for a monad T, that coalgebra structures on a T-algebra can be described in terms of “braidings”, provided that the monad is equipped with an invertible distributive law satisfying the Yang-Baxter equation.