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Our previous paper applied a lopsided version of the Lov\'asz Local Lemma that allows negative dependency graphs to the space of random injections from an $m$-element set to an $n$-element set. Equivalently, the same story can be told about…

Combinatorics · Mathematics 2014-02-25 Linyuan Lu , Laszlo A. Szekely

We delve into the issue of node classification within graphs, specifically reevaluating the concept of neighborhood aggregation, which is a fundamental component in graph neural networks (GNNs). Our analysis reveals conceptual flaws within…

Machine Learning · Computer Science 2024-07-23 Mounir Ghogho

The main result is a common generalization of results on lower bounds for the chromatic number of r-uniform hypergraphs and some of the major theorems in Tverberg-type theory, which is concerned with the intersection pattern of faces in a…

Combinatorics · Mathematics 2017-12-12 Florian Frick

Combinatorics, in particular graph theory, has a rich history of being a domain of successful applications of tools from other areas of mathematics, including topological methods. Here, we survey the study of the Hom-complexes, and the ways…

Algebraic Topology · Mathematics 2007-05-23 Dmitry N. Kozlov

In this note, we investigate some properties of local Kneser graphs defined in [8]. In this regard, as a generalization of the Erd${\rm \ddot{o}}$s-Ko-Rado theorem, we characterize the maximum independent sets of local Kneser graphs. Next,…

Combinatorics · Mathematics 2009-02-24 Meysam Alishahi , Hossein Hajiabolhassan , Ali Taherkhani

Learning graph-structured data with graph neural networks (GNNs) has been recently emerging as an important field because of its wide applicability in bioinformatics, chemoinformatics, social network analysis and data mining. Recent GNN…

Machine Learning · Computer Science 2021-12-16 Cheolhyeong Kim , Haeseong Moon , Hyung Ju Hwang

Motivated by the well-known conjecture of Ryser which relates maximum matchings to minimum vertex covers in $r$-partite $r$-uniform hypergraphs, Lov\'asz formulated a stronger conjecture. It states that one can always reduce the matching…

Combinatorics · Mathematics 2025-07-16 Aida Abiad , Frederik Garbe , Xavier Povill , Christoph Spiegel

Generalized topological spaces in the sense of Cs\'{a}sz\'{a}r have two main features which distinguish them from typical topologies. First, these families of subsets are not closed under intersections. Second, we allow for the possibility…

Logic · Mathematics 2019-09-23 Tomasz Witczak

The fundamental group of a directed graph admits a natural sequence of quotient groups called $r$-fundamental groups, and the $r$-fundamental groups can capture properties of a directed graph that the fundamental group cannot capture. The…

Algebraic Topology · Mathematics 2025-05-26 Daisuke Kishimoto , Yichen Tong

Data-driven neighborhood definitions and graph constructions are often used in machine learning and signal processing applications. k-nearest neighbor~(kNN) and $\epsilon$-neighborhood methods are among the most common methods used for…

Machine Learning · Computer Science 2023-04-18 Sarath Shekkizhar , Antonio Ortega

Kim defined a very general combinatorial abstraction of the diameter of polytopes called subset partition graphs to study how certain combinatorial properties of such graphs may be achieved in lower bound constructions. Using Lov\'asz'…

Combinatorics · Mathematics 2012-03-08 Nicolai Hähnle

To any two graphs G and H one can associate a cell complex Hom(G,H) by taking all graph multihomorphisms from G to H as cells. In this paper we prove the Lovasz Conjecture which states that if Hom(C_{2r+1},G) is k-connected, then…

Combinatorics · Mathematics 2007-05-23 Eric Babson , Dmitry N. Kozlov

The paper surveys recent progress in understanding geometric, topological and combinatorial properties of large simplicial complexes, focusing mainly on ampleness, connectivity and universality. In the first part of the paper we concentrate…

Combinatorics · Mathematics 2023-01-19 Michael Farber

An old result by Shearer relates the Lov\'asz Local Lemma with the independent set polynomial on graphs, and consequently, as observed by Scott and Sokal, with the partition function of the hard core lattice gas on graphs. We use this…

Combinatorics · Mathematics 2010-03-29 Rodrigo Bissacot , Roberto Fernández , Aldo Procacci , Benedetto Scoppola

Rough set theory, a mathematical tool to deal with inexact or uncertain knowledge in information systems, has originally described the indiscernibility of elements by equivalence relations. Covering rough sets are a natural extension of…

Artificial Intelligence · Computer Science 2015-03-13 Ping Zhu

We develop a theory of Euler and Kolyvagin systems relative to the Nekov\'{a}\v{r}--Selmer complexes of $p$-adic representations over local complete Gorenstein rings. This theory is both finer and requires fewer hypotheses than those of…

Number Theory · Mathematics 2026-04-02 Dominik Bullach , David Burns

Alexander $r$-tuples are introduced as a common generalization of pairs of Alexander dual complexes (Alexander $2$-tuples) and $r$-unavoidable complexes of Blagojevi\'{c}, Frick and Ziegler. The associated "Bier complexes" include both the…

Combinatorics · Mathematics 2017-04-13 Duško Jojić , Ilya Nekrasov , Gaiane Panina , Rade Živaljević

The systematic study of neighborhoods of analytic varieties was started by H. Grauert in his celebrated article 1962. In that article he considers a manifold X and a negatively embedded submanifold A subset X. He introduces n-neighborhood,…

Complex Variables · Mathematics 2007-05-23 Cesar Camacho , Hossein Movasati

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

We classify all regular polyhedra according to their type i.e., the collection of numbers of common neighbours that any pair of distinct vertices may have (polyhedra are planar, $3$-connected graphs). As an application, we recover the…

Combinatorics · Mathematics 2026-01-23 Riccardo W. Maffucci