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We study star-based symmetries in uniform hypergraphs and their consequences for matrices whose entries depend only on vertex stars. Such matrices admit a deterministic decomposition into a global component and a local component supported…

Combinatorics · Mathematics 2026-05-19 Kartick Adhikari , Samiron Parui

A graph $G$ contains $H$ as an \emph{immersion} if there is an injective mapping $\phi: V(H)\rightarrow V(G)$ such that for each edge $uv\in E(H)$, there is a path $P_{uv}$ in $G$ joining vertices $\phi(u)$ and $\phi(v)$, and all the paths…

Combinatorics · Mathematics 2022-08-02 Hong Liu , Guanghui Wang , Donglei Yang

We prove a point-wise and average bound for the number of incidences between points and hyper-planes in vector spaces over finite fields. While our estimates are, in general, sharp, we observe an improvement for product sets and sets…

Classical Analysis and ODEs · Mathematics 2007-07-31 Derrick Hart , Alex Iosevich , Doowon Koh , Misha Rudnev

We derive Cheeger inequalities for directed graphs and hypergraphs using the reweighted eigenvalue approach that was recently developed for vertex expansion in undirected graphs [OZ22,KLT22,JPV22]. The goal is to develop a new spectral…

Data Structures and Algorithms · Computer Science 2022-11-18 Lap Chi Lau , Kam Chuen Tung , Robert Wang

Inferring the potential consequences of an unobserved event is a fundamental scientific question. To this end, Pearl's celebrated do-calculus provides a set of inference rules to derive an interventional probability from an observational…

Discrete Mathematics · Computer Science 2021-08-10 Benjamin Heymann , Michel de Lara , Jean-Philippe Chancelier

An oriented hypergraph is a hypergraph where each vertex-edge incidence is given a label of $+1$ or $-1$. We define the adjacency, incidence and Laplacian matrices of an oriented hypergraph and study each of them. We extend several matrix…

Combinatorics · Mathematics 2015-06-17 Nathan Reff , Lucas J. Rusnak

It has become cognitive inertia to employ cross-entropy loss function in classification related tasks. In the untargeted attacks on graph structure, the gradients derived from the attack objective are the attacker's basis for evaluating a…

Machine Learning · Computer Science 2023-04-04 Zihan Liu , Yun Luo , Lirong Wu , Zicheng Liu , Stan Z. Li

We derive upper and lower bounds for the vertex-isoperimetric number of the incidence graphs of unitals and determine its order of magnitude. In the case when a unital contains sufficiently large arcs, these bounds agree and give rise to…

Combinatorics · Mathematics 2017-12-07 Alice M. W. Hui , Muhammad Adib Surani , Sanming Zhou

In this paper we investigate the existence of subexponential parameterized algorithms of three fundamental cycle-hitting problems in geometric graph classes. The considered problems, \textsc{Triangle Hitting} (TH), \textsc{Feedback Vertex…

Data Structures and Algorithms · Computer Science 2024-04-17 Gaétan Berthe , Marin Bougeret , Daniel Gonçalves , Jean-Florent Raymond

Given a graph $G$ and an integer $k$, the Feedback Vertex Set (FVS) problem asks if there is a vertex set $T$ of size at most $k$ that hits all cycles in the graph. The fixed-parameter tractability status of FVS in directed graphs was a…

Data Structures and Algorithms · Computer Science 2014-12-03 Rajesh Chitnis , Marek Cygan , MohammadTaghi Hajiaghayi , Dániel Marx

A vertex-coloring of a hypergraph is conflict-free, if each edge contains a vertex whose color is not repeated on any other vertex of that edge. Let $f(r, \Delta)$ be the smallest integer $k$ such that each $r$-uniform hypergraph of maximum…

Combinatorics · Mathematics 2016-12-06 Maria Axenovich , Jonathan Rollin

Functional brain graphs are often characterized with separate graph-theoretic or spectral descriptors, overlooking how these properties covary and partially overlap across brains and conditions. We anticipate that dense, weighted functional…

Neurons and Cognition · Quantitative Biology 2025-11-07 Subati Abulikemu , Tiago Azevedo , Michail Mamalakis , John Suckling

Let $G$ be a finite undirected graph with edge set $E$. An edge set $E' \subseteq E$ is an {\em induced matching} in $G$ if the pairwise distance of the edges of $E'$ in $G$ is at least two; $E'$ is {\em dominating} in $G$ if every edge $e…

Discrete Mathematics · Computer Science 2011-06-15 Andreas Brandstadt , Raffaele Mosca

P. Erd\H{o}s [On extremal problems of graphs and generalized graphs, Israel Journal of Mathematics 2 (1964), 183-190] characterised those hypergraphs $F$ that have to appear in any sufficiently large hypergraph $H$ of positive density. We…

Combinatorics · Mathematics 2019-01-30 Christian Reiher , Vojtěch Rödl , Mathias Schacht

We show that for any positive integers $g$ and $t$, there is a $K_{6}^{(1)}$-induced-minor-free graph of girth at least $g$ that is not a region intersection graph over the class of $K_t$-minor-free graphs. This answers in a strong form the…

Combinatorics · Mathematics 2025-05-01 Édouard Bonnet , Robert Hickingbotham

The study of entrywise powers of matrices was originated by Loewner in the pursuit of the Bieberbach conjecture. Since the work of FitzGerald and Horn (1977), it is known that $A^{\circ \alpha} := (a_{ij}^\alpha)$ is positive semidefinite…

Combinatorics · Mathematics 2015-11-24 Dominique Guillot , Apoorva Khare , Bala Rajaratnam

For a group $\Gamma$, a $\Gamma$-labelled graph is an undirected graph $G$ where every orientation of an edge is assigned an element of $\Gamma$ so that opposite orientations of the same edge are assigned inverse elements. A path in $G$ is…

Let $G$ be a connected graph and let $F$ be a connected subgraph of $G$ with a given structure. We consider that the centrality of a vertex $i$ of $G$ is determined by the centrality of other vertices in all subgraphs contain $i$ and…

Combinatorics · Mathematics 2024-11-20 Qingying Zhang , Lizhu Sun , Changjiang Bu

Graphs are a powerful way to model interactions and relationships in data from a wide variety of application domains. In this setting, entities represented by vertices at the "center" of the graph are often more important than those…

Social and Information Networks · Computer Science 2014-11-06 Michael P. O'Brien , Blair D. Sullivan

In this paper, we introduce VACA, a novel class of variational graph autoencoders for causal inference in the absence of hidden confounders, when only observational data and the causal graph are available. Without making any parametric…

Machine Learning · Statistics 2021-10-29 Pablo Sanchez-Martin , Miriam Rateike , Isabel Valera
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