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The stability number of a graph G, denoted by alpha(G), is the cardinality of a stable set of maximum size in G. A graph is well-covered if every maximal stable set has the same size. G is a Koenig-Egervary graph if its order equals…

Combinatorics · Mathematics 2007-05-23 Vadim E. Levit , Eugen Mandrescu

An independent set in a graph G is a set of vertices no two of which are joined by an edge. A vertex-weighted graph associates a weight with every vertex in the graph. A vertex-weighted graph G is called a unique independence…

Computational Complexity · Computer Science 2009-07-02 Farzad Didehvar , Ali D. Mehrabi , Fatemeh Raee B

When $H$ is a forest, the Gy\'arf\'as-Sumner conjecture implies that every graph $G$ with no induced subgraph isomorphic to $H$ and with bounded clique number has a stable set of linear size. We cannot prove that, but we prove that every…

Combinatorics · Mathematics 2025-07-21 Tung Nguyen , Alex Scott , Paul Seymour

A graph is said to be distance-hereditary if the distance function in every connected induced subgraph is the same as in the graph itself. We prove that the ordinary Weisfeiler-Leman algorithm correctly tests the isomorphism of any two…

Combinatorics · Mathematics 2020-05-26 Alexander L. Gavrilyuk , Roman Nedela , Ilia Ponomarenko

For any edge weight distribution, we consider the uniform spanning tree (UST) on finite graphs with i.i.d. random edge weights. We show that, for bounded degree expander graphs and finite boxes of ${\mathbb Z}^d$, the diameter of the UST is…

Probability · Mathematics 2024-10-23 Luca Makowiec , Michele Salvi , Rongfeng Sun

We introduce a refinement of the persistence diagram, the graded persistence diagram. It is the Mobius inversion of the graded rank function, which is obtained from the rank function using the unary numeral system. Both persistence diagrams…

Algebraic Topology · Mathematics 2022-05-09 Leo Betthauser , Peter Bubenik , Parker B. Edwards

The complexity of a finite connected graph is its number of spanning trees; for a non-connected graph it is the product of complexities of its connected components. If $G$ is an infinite graph with cofinite free ${\mathbb Z}^d$-symmetry,…

Combinatorics · Mathematics 2016-02-10 Daniel S. Silver , Susan G. Williams

We investigate random connected graphs from a block-stable class whose distribution is weighted based on the number of $2$-connected components, or blocks. This includes the class of planar graphs. For this, we develop a notion of a…

Combinatorics · Mathematics 2026-04-28 Mihyun Kang , Zéphyr Salvy , Ronen Wdowinski

We present a concept called the branch-depth of a connectivity function, that generalizes the tree-depth of graphs. Then we prove two theorems showing that this concept aligns closely with the notions of tree-depth and shrub-depth of graphs…

Combinatorics · Mathematics 2020-11-05 Matt DeVos , O-joung Kwon , Sang-il Oum

We define an algorithm k which takes a connected graph G on a totally ordered vertex set and returns an increasing tree R (which is not necessarily a subtree of G). We characterize the set of graphs G such that k(G)=R. Because this set has…

Combinatorics · Mathematics 2007-05-23 Gus Wiseman

Let G be a finite undirected graph. A vertex dominates itself and all its neighbors in G. A vertex set D is an efficient dominating set (e.d. for short) of G if every vertex of G is dominated by exactly one vertex of D. The Efficient…

Discrete Mathematics · Computer Science 2013-04-24 Andreas Brandstädt , Martin Milanic , Ragnar Nevries

Let $\mathcal G$ be a separable family of graphs. Then for all positive constants $\epsilon$ and $\Delta$ and for every sufficiently large integer $n$, every sequence $G_1,\dotsc,G_t\in\mathcal G$ of graphs of order $n$ and maximum degree…

Combinatorics · Mathematics 2016-06-01 Asaf Ferber , Choongbum Lee , Frank Mousset

A polynomial is said to be unimodal if its coefficients are non-decreasing and then non-increasing. The domination polynomial of a graph $G$ is the generating function of the number of dominating sets of each cardinality in $G$. In…

Combinatorics · Mathematics 2024-11-05 Iain Beaton , Sam Schoonhoven

Motivated by a question of Galby, Munaro, and Yang (SoCG 2023) asking whether every graph class of bounded layered tree-independence number admits clique-based separators of sublinear weight, we investigate relations between layered…

Combinatorics · Mathematics 2025-06-17 Clément Dallard , Martin Milanič , Andrea Munaro , Shizhou Yang

The independence polynomial of a graph is termed {\it stable} if all its roots are located in the left half-plane $\{z \in \mathbb{C} : \mathrm{Re}(z) \leq 0\}$, and the graph itself is also referred to as stable. Brown and Cameron…

Combinatorics · Mathematics 2025-06-02 Guo Chen , Bo Ning , Jianhua Tu

Let $\mathcal{G}_{n,r,s}$ denote a uniformly random $r$-regular $s$-uniform hypergraph on the vertex set $\{1,2,\ldots, n\}$. We establish a threshold result for the existence of a spanning tree in $\mathcal{G}_{n,r,s}$, restricting to $n$…

Combinatorics · Mathematics 2023-06-22 Catherine Greenhill , Mikhail Isaev , Gary Liang

The {\em independent domination number} $\gamma^i(G)$ of a graph $G$ is the maximum, over all independent sets $I$, of the minimal number of vertices needed to dominate $I$. It is known \cite{abz} that in chordal graphs $\gamma^i$ is equal…

Combinatorics · Mathematics 2017-09-29 Ron Aharoni , Irina Gorelik

Alon and Wormald showed that any graph with minimum degree d contains a spanning star forest in which every connected component is of size at least \Omega((d/\log d)^{1/3}). They asked if any connected graph with minimum degree at least d…

Combinatorics · Mathematics 2016-07-20 Codrut Grosu

Consider~\(n\) nodes~\(\{X_i\}_{1 \leq i \leq n}\) independently distributed in the unit square~\(S,\) each according to a distribution~\(f.\) Nodes~\(X_i\) and~\(X_j\) are joined by an edge if the Euclidean distance~\(d(X_i,X_j)\) is less…

Probability · Mathematics 2021-03-02 Ghurumuruhan Ganesan

Let $G$ be a nontrivial graph with minimum degree $\delta$ and $k$ an integer with $k\ge 2$. In the literature, there are eigenvalue conditions that imply $G$ contains $k$ edge-disjoint spanning trees. We give eigenvalue conditions that…

Combinatorics · Mathematics 2025-04-02 Jin Cai , Bo Zhou