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We prove a new signed elementary symmetric function expansion of the chromatic quasisymmetric function of any natural unit interval graph. We then use a sign-reversing involution to prove a new combinatorial formula for K-chains, which are…

Combinatorics · Mathematics 2024-05-09 Foster Tom

Spectral clustering is a well-known technique which identifies $k$ clusters in an undirected graph with weight matrix $W\in\mathbb{R}^{n\times n}$ by exploiting its graph Laplacian $L(W)$, whose eigenvalues $0=\lambda_1\leq \lambda_2 \leq…

Numerical Analysis · Mathematics 2023-06-08 Nicola Guglielmi , Stefano Sicilia

An oriented hypergraph is a hypergraph together with an incidence orientation such that each edge-vertex incidence is given a label of $+1$ or $-1$. An oriented hypergraph is called incidence balanced if there exists a bipartition of the…

Combinatorics · Mathematics 2021-08-31 Yi Wang , Le Wang , Yi-Zheng Fan

Spectral clustering is widely used in practice due to its flexibility, computational efficiency, and well-understood theoretical performance guarantees. Recently, spectral clustering has been studied to find balanced clusters under…

Machine Learning · Statistics 2022-03-07 Shubham Gupta , Ambedkar Dukkipati

A claw-free graph is a graph that does not contain $K_{1,3}$ as an induced subgraph, and a 2-factor is a 2-regular spanning subgraph of a graph. In 1997, Ryj\'{a}\v{c}ek introduced the closure concept of claw-free graphs, and Hamilton…

Combinatorics · Mathematics 2025-04-14 Masaki Kashima

In order to study real-world systems, many applied works model them through signed graphs, i.e. graphs whose edges are labeled as either positive or negative. Such a graph is considered as structurally balanced when it can be partitioned…

Robotics · Computer Science 2022-03-31 Nejat Arinik , Rosa Figueiredo , Vincent Labatut

In \cite{Elek} we proved that the limit of a weakly convergent sequence of finite graphs can be viewed as a graphing or a continuous field of infinite graphs. Thus one can associate a type $II_1$-von Neumann algebra to such graph sequences.…

Combinatorics · Mathematics 2007-05-23 Gábor Elek

For a simple graph G = (V, E) and a positive integer k greater than or equal to 2, a coloring of vertices of G using exactly k colors such that each vertex has an equal number of neighbors of each color is called neighborhood-balanced…

Combinatorics · Mathematics 2025-09-09 Maurice Genevieva Almeida , Tarkeshwar Singh , Siddharth Gupta , Ravindra Pawar

Connected clustering denotes a family of constrained clustering problems in which we are given a distance metric and an undirected connectivity graph $G$ that can be completely unrelated to the metric. The aim is to partition the $n$…

Data Structures and Algorithms · Computer Science 2025-11-25 Jan Eube , Heiko Röglin

Let $\Gamma=(G,\sigma)$ be a signed graph, where $\sigma$ is the sign function on the edges of $G$. The adjacency matrix of $\Gamma=(G, \sigma)$ is a square matrix $A(\Gamma)=A(G, \sigma)=\left(a_{i j}^{\sigma}\right)$, where $a_{i…

Combinatorics · Mathematics 2021-11-16 S. Pirzada , Tahir Shamsher , Mushtaq A. Bhat

This work derives an upper bound on the maximum cardinality of a family of graphs on a fixed number of vertices, in which the intersection of every two graphs in that family contains a subgraph that is isomorphic to a specified graph H.…

Combinatorics · Mathematics 2025-05-23 Igal Sason

In the first part of this paper, we survey results that are associated with three types of Laplacian matrices:difference, normalized, and signless. We derive eigenvalue and eigenvector formulaes for paths and cycles using circulant matrices…

Combinatorics · Mathematics 2012-11-06 K. K. K. R. Perera , Yoshihiro Mizoguchi

Signed graphs encode positive (attractive) and negative (repulsive) relations between nodes. We extend spectral clustering to signed graphs via the one-parameter family of Signed Power Mean Laplacians, defined as the matrix power mean of…

Machine Learning · Computer Science 2019-05-16 Pedro Mercado , Francesco Tudisco , Matthias Hein

We consider the problem of spectral clustering under group fairness constraints, where samples from each sensitive group are approximately proportionally represented in each cluster. Traditional fair spectral clustering (FSC) methods…

Machine Learning · Computer Science 2023-11-27 Xiang Zhang , Qiao Wang

A complete $k$-coloring of a graph $G$ is a (not necessarily proper) $k$-coloring of the vertices of $G$, such that each pair of different colors appears in an edge. A complete $k$-coloring is also called connected, if each color class…

Combinatorics · Mathematics 2018-10-01 G. Araujo-Pardo , C. Rubio-Montiel

Spectral Clustering as a relaxation of the normalized/ratio cut has become one of the standard graph-based clustering methods. Existing methods for the computation of multiple clusters, corresponding to a balanced $k$-cut of the graph, are…

Machine Learning · Statistics 2015-05-26 Syama Sundar Rangapuram , Pramod Kaushik Mudrakarta , Matthias Hein

A signed graph $(G,\sigma)$ consists of a graph $G$ and the signature $\sigma : E(G) \rightarrow \{+1,-1\}$. An incidence of $G$ is a pair $(v,e)$, where $v$ is one of the end vertices of an edge $e \in E(G)$. A proper $q$-edge coloring…

Combinatorics · Mathematics 2026-02-23 Deepak Sehrawat , Rohit

Let $G$ be a Cayley graph of the elementary abelian $2$-group $\mathbb{Z}_2^{n}$ with respect to a set $S$ of size $d$. We prove that for any such $G, S$ and $d$, the maximum degree of any induced subgraph of $G$ on any set of more than…

Combinatorics · Mathematics 2020-11-10 Noga Alon , Kai Zheng

In this study, we address the complex issue of graph clustering in signed graphs, which are characterized by positive and negative weighted edges representing attraction and repulsion among nodes, respectively. The primary objective is to…

Data Structures and Algorithms · Computer Science 2024-07-10 Felix Hausberger , Marcelo Fonseca Faraj , Christian Schulz

Complex unit gain graphs may exhibit various kinds of symmetry. In this work, we explore structural symmetry, spectral symmetry and sign-symmetry in such graphs, and their respective relations to one-another. Our main result is a…

Combinatorics · Mathematics 2024-10-04 Pepijn Wissing , Edwin R. van Dam