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Monads are a popular tool for the working functional programmer to structure effectful computations. This paper presents polymonads, a generalization of monads. Polymonads give the familiar monadic bind the more general type forall a,b. L a…

Programming Languages · Computer Science 2014-06-10 Michael Hicks , Gavin Bierman , Nataliya Guts , Daan Leijen , Nikhil Swamy

We prove that the opposite of the category of coalgebras for the Vietoris endofunctor on the category of compact Hausdorff spaces is monadic over Set. We deliver an analogous result for the upper, lower and convex Vietoris endofunctors…

Logic · Mathematics 2025-09-17 Marco Abbadini , Ivan Di Liberti

It is known that the so-called monadic decomposition, applied to the adjunction connecting the category of bialgebras to the category of vector spaces via the tensor and the primitive functors, returns the usual adjunction between…

Category Theory · Mathematics 2021-02-15 Alessandro Ardizzoni , Claudia Menini

Presentations of categories are a well-known algebraic tool to provide descriptions of categories by means of generators, for objects and morphisms, and relations on morphisms. We generalize here this notion, in order to consider situations…

Logic in Computer Science · Computer Science 2019-03-14 Pierre-Louis Curien , Samuel Mimram

We show that every gammoid has special digraph representations, such that a representation of the dual of the gammoid may be easily obtained by reversing all arcs. In an informal sense, the duality notion of a poset applied to the digraph…

Combinatorics · Mathematics 2022-06-07 Immanuel Albrecht

A duality between the category of convex spaces and measurable spaces arises from the existence of the unit interval, which is an object in both these categories. The full subcategory of the category of convex spaces, consisting of just the…

Category Theory · Mathematics 2017-07-04 Kirk Sturtz

Monads are well known to be equivalent to lax functors out of the terminal category. Morita contexts are here shown to be lax functors out of the chaotic category with two objects. This allows various aspects in the theory of Morita…

Category Theory · Mathematics 2014-05-21 Stephen Lack

We extend Willerton's graphical calculus for bimonads to comodule monads, a monadic interpretation of module categories over a monoidal category. As an application, we prove a version of Tannaka--Krein duality for these structures.

Category Theory · Mathematics 2024-08-30 Sebastian Halbig , Tony Zorman

In this paper, we introduce and investigate monadic NM-algebras: a variety of NM-algebras equipped with universal quantifiers. Also, we obtain some conditions under which monadic NM-algebras become monadic Boolean algebras. Besides, we show…

Logic · Mathematics 2017-09-15 Jun Tao Wang , Xiao Long Xin , Peng Fei He

The goal of this paper is to prove coherence results with respect to relational graphs for monoidal monads and comonads, i.e. monads and comonads in a monoidal category such that the endofunctor of the monad or comonad is a monoidal functor…

Category Theory · Mathematics 2010-01-08 K. Dosen , Z. Petric

We generalize the correspondence between theories and monads with arities of arXiv:1101.3064 to $\infty$-categories. Additionally, we introduce the notion of complete theories that is unique to the $\infty$-categorical case and provide a…

Category Theory · Mathematics 2021-06-01 Roman Kositsyn

In a recent paper, Amini et al. introduce a general framework to prove duality theorems between special decompositions and their dual combinatorial object. They thus unify all known ad-hoc proofs in one single theorem. While this…

Discrete Mathematics · Computer Science 2009-10-20 Laurent Lyaudet , Frédéric Mazoit , Stephan Thomasse

We develop and investigate a general theory of representations of second-order functionals, based on a notion of a right comodule for a monad on the category of containers. We show how the notion of comodule representability naturally…

Logic in Computer Science · Computer Science 2025-06-12 Danel Ahman , Andrej Bauer

We extend Makkai duality between coherent toposes and ultracategories to a duality between toposes with enough points and ultraconvergence spaces. Our proof generalizes and simplifies Makkai's original proof. Our main result can also be…

Category Theory · Mathematics 2026-02-24 Sam van Gool , Jérémie Marquès , Umberto Tarantino

The principle behind algebraic language theory for various kinds of structures, such as words or trees, is to use a compositional function from the structures into a finite set. To talk about compositionality, one needs some way of…

Logic in Computer Science · Computer Science 2015-02-18 Mikołaj Bojańczyk

Strong functors and monads are ubiquitous in Computer Science. More recently, comonads have demonstrated their use in structuring context-dependent notions of computation. However, the dualisation of ``being strong'' property passed somehow…

Logic in Computer Science · Computer Science 2025-09-17 Adriana Balan , Silviu-George Pantelimon

Given two monads $S$, $T$ on a category where idempotents split, and a weak distributive law between them, one can build a combined monad $U$. Making explicit what this monad $U$ is requires some effort. When we already have an idea what…

Logic in Computer Science · Computer Science 2025-11-04 Jean Goubault-Larrecq

Density functions that represent sample data are often multimodal, i.e. they exhibit more than one maximum. Typically this behavior is taken to indicate that the underlying data deserves a more detailed representation as a mixture of…

Methodology · Statistics 2018-06-04 Steve Huntsman

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 compactifications inherit their…

General Topology · Mathematics 2024-07-17 Ando Razafindrakoto

The algebraic properties of the combination of probabilistic choice and nondeterministic choice have long been a research topic in program semantics. This paper explains a formalization in the Coq proof assistant of a monad equipped with…

Logic in Computer Science · Computer Science 2023-12-12 Reynald Affeldt , Jacques Garrigue , David Nowak , Takafumi Saikawa