惯性聚合 高效追踪和阅读你感兴趣的博客、新闻、科技资讯
阅读原文 在惯性聚合中打开

推荐订阅源

罗磊的独立博客
小众软件
小众软件
The Cloudflare Blog
博客园 - 【当耐特】
钛媒体:引领未来商业与生活新知
钛媒体:引领未来商业与生活新知
酷 壳 – CoolShell
酷 壳 – CoolShell
WordPress大学
WordPress大学
freeCodeCamp Programming Tutorials: Python, JavaScript, Git & More
V
Visual Studio Blog
量子位
奇客Solidot–传递最新科技情报
奇客Solidot–传递最新科技情报
美团技术团队
S
SegmentFault 最新的问题
宝玉的分享
宝玉的分享
博客园 - 叶小钗
月光博客
月光博客
Apple Machine Learning Research
Apple Machine Learning Research
T
Tailwind CSS Blog
博客园 - 聂微东
OSCHINA 社区最新新闻
OSCHINA 社区最新新闻
J
Java Code Geeks
Y
Y Combinator Blog
D
Docker
Microsoft Azure Blog
Microsoft Azure Blog

math.CO updates on arXiv.org

Complement Submodular Information Measures for Balanced and Robust Data Selection A Proof of a Conjecture on Positive and Negative Square Energies of Unicyclic Graphs Laplacian Spectrum of the Weakly Zero-Divisor Graph of a Finite Commutative Ring An identity for second Eulerian numbers via lattice-point counting $t$-tone edge coloring of graphs Constructing Maximal Bumpless Pipedreams for Double Grothendieck Polynomials Mubayi's Polynomial-Ideal Conjecture and Cover-Ideal Turán Methods Implicit Binarization via Complex Phase Dynamics in Combinatorial Optimization The limits of Schur multipliers in Pólya conversion problems for the $q$-permanent function Universality theorems for generalized splines Framing Triangulations for Arbitrary Integer Flow Polytopes On the Common Generalization of Gentle Algebras and Framed Directed Acyclic Graphs The complexity of frugal digraph homomorphisms Chaotic and periodic behavior of jeu de taquin on infinite Young tableaux Enumerating Pattern Avoiding Parking Functions Incidence toric ideals and three-point functions Unique Winning Opening Move in Three-Row Chomp Strong majority colorings of graphs A Balancing Theorem for Spanning Trees of Rectangular Grid Graphs Spectral radius and edge-disjoint connected factors of graphs New invariants for rank metric codes, with applications to the classification of rank two semifields of order 256 Flexible DP-4-coloring of planar graphs without 4-cycles and intersecting triangles Balanced intersection size distributions in projective planes List Reconstruction Problem with List Size Two Is Dimensionality a Barrier for Retrieval Models? The INIEP: Irreducible and Positive Realizations The number of Pfaffian orientations on punctured polygonally cellulated surfaces Explicit Construction of Polytopes whose Ehrhart Polynomials Realize any Given Sign Pattern Finite-state enumeration of adjacency-constrained 132-avoiding permutations AMDS and quantum AMDS Constacyclic codes of length $4p^ς$ over $\mathbb{F}_{{p}^{m}}$
Isolation of regular graphs, stars and $k$-chromatic graphs
Peter Borg · 2023-03-24 · via math.CO updates on arXiv.org

Given a set $\mathcal{F}$ of graphs, we call a copy of a graph in $\mathcal{F}$ an $\mathcal{F}$-graph. The $\mathcal{F}$-isolation number of a graph $G$, denoted by $ι(G,\mathcal{F})$, is the size of a smallest set $D$ of vertices of $G$ such that the closed neighbourhood of $D$ intersects the vertex sets of the $\mathcal{F}$-graphs contained by $G$ (equivalently, $G - N[D]$ contains no $\mathcal{F}$-graph). Thus, $ι(G,\{K_1\})$ is the domination number of $G$. Clearly, $ι(G, \mathcal{F}) \leq ι(G, \mathcal{F} \cup \mathcal{H})$. For any integer $k \geq 1$, let $\mathcal{F}_{0,k}$ be the set consisting of the $k$-star $K_{1,k}$, let $\mathcal{F}_{1,k}$ be the set of regular graphs whose degree is at least $k-1$, let $\mathcal{F}_{2,k}$ be the set of graphs whose chromatic number is at least $k$, and let $\mathcal{F}_{3,k}$ be the union $\mathcal{F}_{0,k} \cup \mathcal{F}_{1,k} \cup \mathcal{F}_{2,k}$. We prove that if $G$ is a connected $n$-vertex graph, then $ι(G, \mathcal{F}_{3,k}) \leq \frac{n}{k+1}$ unless $G$ is a $k$-clique or $k = 2$ and $G$ is a $5$-cycle. This generalizes a classical bound of Ore on the domination number, a bound of Caro and Hansberg and of Żyliński on the vertex-edge domination number, a bound of Fenech, Kaemawichanurat and the author on the $k$-clique isolation number, a bound of the author on the cycle isolation number, and a bound of Caro and Hansberg on the $\mathcal{F}_{0,k}$-isolation number. The proof features a new strategy. For $i = 1, 2, 3$, the bound $\frac{n}{k+1}$ on $ι(G, \mathcal{F}_{i,k})$ is attainable if $k+1$ divides $n$. Our second main result is that the bound $\frac{n}{k+1}$ on $ι(G, \mathcal{F}_{0,k})$ is attainable if and only if $n$ is $0$ or $k+1$ or $2(k+1)$. We pose some problems and conjectures, and establish additional intriguing phenomena concerning $k$-star isolation and $k$-cycle isolation.