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The method of little groups describes the irreducible characters of semidirect products with abelian normal subgroups in terms of the irreducible characters of the factor groups. We modify this method to construct supercharacter theories of…

Representation Theory · Mathematics 2016-04-28 Scott Andrews

We obtain sharp bounds for the number of n-cycles in a finite graph as a function of the number of edges, and prove that the complete graph is optimal in more ways than could be imagined. En route, we prove some sharp estimates on power…

Combinatorics · Mathematics 2007-05-23 Igor Rivin

We consider hereditary classes of graphs equipped with a total order. We provide multiple equivalent characterisations of those classes which have bounded twin-width. In particular, we prove a grid theorem for classes of ordered graphs…

Logic in Computer Science · Computer Science 2021-07-07 Pierre Simon , Szymon Toruńczyk

In this work, some combinatorial lower bound for regularity of powers of the edge ideal of a uniform hypergarph is gained. A family of hypergraphs whose regularity of edge ideal attains this bound and has a significant difference from the…

Commutative Algebra · Mathematics 2025-06-03 Fahimeh Khosh-Ahang Ghasr

We demonstrate that graph-based models are fully capable of representing higher-order interactions, and have a long history of being used for precisely this purpose. This stands in contrast to a common claim in the recent literature on…

Physics and Society · Physics 2026-02-20 Tiago P. Peixoto , Leto Peel , Thilo Gross , Manlio De Domenico

G\'abor Elek introduced the notion of a hyperfinite graph family: a collection of graphs is hypefinite if for every $\epsilon>0$ there is some finite $k$ such that each graph $G$ in the collection can be broken into connected components of…

Probability · Mathematics 2007-11-27 Oded Schramm

In comparison to graphs, combinatorial methods for the isomorphism problem of finite groups are less developed than algebraic ones. To be able to investigate the descriptive complexity of finite groups and the group isomorphism problem, we…

Logic in Computer Science · Computer Science 2021-11-24 Jendrik Brachter , Pascal Schweitzer

We find an asymptotic enumeration formula for the number of simple $r$-uniform hypergraphs with a given degree sequence, when the number of edges is sufficiently large. The formula is given in terms of the solution of a system of equations.…

Combinatorics · Mathematics 2022-05-18 Catherine Greenhill , Mikhail Isaev , Tamás Makai , Brendan D. McKay

We show the existence of and explicitly construct generic polynomials for various groups, over fields of positive characteristic. The methods we develop apply to a broad class of connected linear algebraic groups defined over finite fields…

Number Theory · Mathematics 2016-01-19 Eric Y. Chen , J. T. Ferrara , Liam Mazurowski

We introduce $k$-robust clique complexes, a family of simplicial complexes that generalizes the traditional clique complex. Here, a subset of vertices forms a simplex provided it does not contain an independent set of size $k$. We…

Combinatorics · Mathematics 2026-04-02 Marek Filakovský

Counterfactual examples have emerged as an effective approach to produce simple and understandable post-hoc explanations. In the context of graph classification, previous work has focused on generating counterfactual explanations by…

Machine Learning · Computer Science 2023-07-28 Carlo Abrate , Giulia Preti , Francesco Bonchi

Ordering theorems, characterizing when partial orders of a group extend to total orders, are used to generate hypersequent calculi for varieties of lattice-ordered groups (l-groups). These calculi are then used to provide new proofs of…

Logic · Mathematics 2017-08-03 Almudena Colacito , George Metcalfe

We enumerate the independent sets of several classes of regular and almost regular graphs and compute the corresponding generating functions. We also note the relations between these graphs and other combinatorial objects and, in some…

Combinatorics · Mathematics 2007-05-23 Alexander Burstein , Sergey Kitaev , Toufik Mansour

Ryser's Conjecture states that any $r$-partite $r$-uniform hypergraph has a vertex cover of size at most $r - 1$ times the size of the largest matching. For $r = 2$, the conjecture is simply K\"onig's Theorem and every bipartite graph is a…

Combinatorics · Mathematics 2016-06-21 Penny Haxell , Lothar Narins , Tibor Szabó

A major theme in arithmetic combinatorics is proving multiple recurrence results on semigroups (such as Szemer\'edi's theorem) and this can often be done using methods of ergodic Ramsey theory. What usually lies at the heart of such proofs…

Logic · Mathematics 2017-04-18 Anush Tserunyan

We identify the (filter representation of the) logic behind the recent theory of coherent sets of desirable (sets of) things, which generalise coherent sets of desirable (sets of) gambles as well as coherent choice functions, and show that…

Logic · Mathematics 2024-06-21 Gert de Cooman , Arthur Van Camp , Jasper De Bock

Let $L$ be the language of rings. We provide an axiomatization of the $L$-theories of quaternions and octonions and characterize their models: they coincide, up to isomorphism, with quaternion and octonion algebras over a real closed field,…

Algebraic Geometry · Mathematics 2026-05-05 Enrico Savi

We present a simple mechanism, which can be randomised, for constructing sparse $3$-uniform hypergraphs with strong expansion properties. These hypergraphs are constructed using Cayley graphs over $\mathbb{Z}_2^t$ and have vertex degree…

Combinatorics · Mathematics 2019-06-26 David Conlon

We study several extensions of the notion of perfect graphs to $k$-uniform hypergraphs.

Combinatorics · Mathematics 2022-10-04 Maria Chudnovsky , Gil Kalai

Our work builds on known results for k-uniform hypergraphs including the existence of limits, a Regularity Lemma and a Removal Lemma. Our main tool here is a theory of measures on ultraproduct spaces which establishes a correspondence…

Logic · Mathematics 2014-12-30 Ashwini Aroskar , James Cummings