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We prove the bounded packing property for any abelian subgroup of a group acting properly and cocompactly on a CAT(0) cube complex. A main ingredient of the proof is a cubical flat torus theorem. This ingredient is also used to show that…

Group Theory · Mathematics 2017-03-14 Daniel T. Wise , Daniel J. Woodhouse

Delta lenses are functors equipped with a suitable choice of lifts, generalising the notion of split opfibration. In recent work, delta lenses were characterised as the right class of an algebraic weak factorisation system. In this paper,…

Category Theory · Mathematics 2024-08-09 Bryce Clarke

We generalize the work by Soboci\'nski on relational presheaves and their connection with weak (bi)simulation for labelled transistion systems to a coalgebraic setting. We show that the coalgebraic notion of saturation studied in our…

Logic in Computer Science · Computer Science 2015-11-03 Tomasz Brengos

We discuss the folklore construction of the Gray tensor product of 2-categories as obtained by factoring the map from the funny tensor product to the cartesian product. We show that this factorisation can be obtained without using a…

Category Theory · Mathematics 2022-01-31 John Bourke , Nick Gurski

Let $G$ be a group. We can topologize the spaces of left-orderings $LO(G)$ and bi-orderings $O(G)$ of $G$ with the product topology. These spaces may or may not have isolated points. It is known that $LO(F_n)$ has no isolated points, where…

Group Theory · Mathematics 2023-04-12 Serhii Dovhyi , Kyrylo Muliarchyk

Mott noted a one-to-one correspondence between saturated multiplicatively closed subsets of a domain D and directed convex subgroups of the group of divisibility D. With this, we construct a functor between inclusions into saturated…

Commutative Algebra · Mathematics 2016-12-15 Jim Coykendall , Brandon Goodell

For a semisimple multiring category with left duals, we prove that the unit object is simple if and only if the tensor functors by any non-zero algebra are separable (resp. faithful, resp. Maschke, resp. dual Maschke, resp. conservative).…

Category Theory · Mathematics 2026-02-10 Zhenbang Zuo

It is shown how to construct *-homomorphic quantum stochastic Feller cocycles for certain unbounded generators, and so obtain dilations of strongly continuous quantum dynamical semigroups on C* algebras; this generalises the construction of…

Functional Analysis · Mathematics 2013-05-06 Alexander C. R. Belton , Stephen J. Wills

We present a combinatorial structure of generators of $D(\mathcal{A}).$ This structure permits us to detect the relationship between the combinatorial determined property and the singularity of vector field. Consequently, by using only…

Combinatorics · Mathematics 2024-05-13 Tran Quoc Cong

Let $d(G)$ be the smallest cardinality of a generating set of a finite group $G.$ We give a complete classification of the finite groups with the property that, whenever $ \langle x_1, \dots, x_{d(G)} \rangle = \langle y_1, \dots, y_{d(G)}…

Group Theory · Mathematics 2025-06-03 Andrea Lucchini , Patricia Medina Capilla

We show how the $S$-matrix of an extended theory of gravity defined by its three-point amplitudes can be constructed by demanding factorisation. The resultant $S$-matrix has tree amplitudes obeying the same soft singularity theorems as…

High Energy Physics - Theory · Physics 2017-05-24 David C. Dunbar , John H. Godwin , Guy R. Jehu , Warren B. Perkins

It is well-known in universal algebra that adding structure and equational axioms generates forgetful functors between varieties, and such functors all have left adjoints. The category of elementary doctrines provides a natural framework…

Category Theory · Mathematics 2024-05-14 Francesca Guffanti

Expanding on the comprehensive factorization of functors internal to a category C, under fairly mild conditions on a monad T on C we establish that this orthogonal factorization system exists even in Burroni's category Cat(T) of (internal)…

Category Theory · Mathematics 2020-12-16 Walter Tholen , Leila Yeganeh

Assuming a large cardinal hypothesis, Laver gave a representation of the monogenerated free left distributive algebra (LDA) using elementary embeddings and used this representation to prove many algebraic results. Some of these results were…

Logic · Mathematics 2026-04-13 Scott Cramer , Meng-Che "Turbo" Ho , Sheila K. Miller Edwards , Nam Trang

We construct irreducible unitary representations of a finitely generated free group which are weakly contained in the left regular representation and in which a given linear combination of the generators has an eigenvalue. When the…

Operator Algebras · Mathematics 2007-05-23 William L. Paschke

We consider dual frames generated by actions of countable discrete groups on a Hilbert space. Module frames in a class of modules over a group algebra are shown to coincide with a class of ordinary frames in a representation of the group.…

Functional Analysis · Mathematics 2009-11-24 Kjetil Roysland

We give an elementary construction of the exact completion of a weakly lex category for categories enriched in the cartesian closed category $\mathsf{Pos}$ of partially ordered sets. Paralleling the ordinary case, we characterize categories…

Category Theory · Mathematics 2025-12-16 Vasileios Aravantinos-Sotiropoulos

Bilinear maps and their classifying tensor products are well-known in the theory of linear algebra, and their generalization to algebras of commutative monads is a classical result of monad theory. Motivated by constructions needed in…

Category Theory · Mathematics 2022-05-12 Tomáš Jakl , Dan Marsden , Nihil Shah

For an arbitrary rational polyhedron we consider its decompositions into Minkowski summands and, dual to this, the free extensions of the associated pair of semigroups. Being free for the pair of semigroups is equivalent to flatness for the…

Algebraic Geometry · Mathematics 2020-04-17 Klaus Altmann , Alexandru Constantinescu , Matej Filip

We use edge slidings and saturated disjoint Borel families to give a conceptually simple proof of Hjorth's theorem on cost attained: if a countable p.m.p. ergodic equivalence relation $E$ is treeable and has cost $n \in \mathbb{N} \cup…

Dynamical Systems · Mathematics 2018-07-31 Benjamin D. Miller , Anush Tserunyan