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Related papers: A note on potentially $K_4-e$ graphical sequences

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A sequence $S$ is potentially $K_{m}-C_{4}$-graphical if it has a realization containing a $K_{m}-C_{4}$ as a subgraph. Let $\sigma(K_{m}-C_{4}, n)$ denote the smallest degree sum such that every $n$-term graphical sequence $S$ with…

Combinatorics · Mathematics 2007-08-30 Chunhui Lai

A sequence $S$ is potentially $K_{m}-P_{k}$ graphical if it has a realization containing a $K_{m}-P_{k}$ as a subgraph. Let $\sigma(K_{m}-P_{k}, n)$ denote the smallest degree sum such that every $n$-term graphical sequence $S$ with…

Combinatorics · Mathematics 2007-05-23 Chunhui Lai

Let $K_{m}-H$ be the graph obtained from $K_{m}$ by removing the edges set $E(H)$ of the graph $H$ ($H$ is a subgraph of $K_{m}$). We use the symbol $Z_4$ to denote $K_4-P_2.$ A sequence $S$ is potentially $K_{m}-H$-graphical if it has a…

Combinatorics · Mathematics 2009-11-17 Chunhui Lai

A sequence $S$ is potentially $K_{p_{1},p_{2},...,p_{t}}$ graphical if it has a realization containing a $K_{p_{1},p_{2},...,p_{t}}$ as a subgraph, where $K_{p_{1},p_{2},...,p_{t}}$ is a complete t-partite graph with partition sizes…

Combinatorics · Mathematics 2007-05-23 Chunhui Lai

Let $K_{m}-H$ be the graph obtained from $K_{m}$ by removing the edges set $E(H)$ of the graph $H$ ($H$ is a subgraph of $K_{m}$). We use the symbol $Z_4$ to denote $K_4-P_2.$ A sequence $S$ is potentially $K_{m}-H$-graphical if it has a…

Combinatorics · Mathematics 2009-11-15 Chunhui Lai , Guiying Yan

A sequence $S$ is potentially $K_{m}-H$-graphical if it has a realization containing a $K_{m}-H$ as a subgraph. Let $\sigma(K_{m}-H, n)$ denote the smallest degree sum such that every $n$-term graphical sequence $S$ with $\sigma(S)\geq…

Combinatorics · Mathematics 2009-11-17 Chunhui Lai , Yuzhen Sun

A sequence $S$ is potentially $K_{p,1,1}$ graphical if it has a realization containing a $K_{p,1,1}$ as a subgraph, where $K_{p,1,1}$ is a complete 3-partite graph with partition sizes $p,1,1$. Let $\sigma(K_{p,1,1}, n)$ denote the smallest…

Combinatorics · Mathematics 2007-05-23 Chunhui Lai

In this paper we consider a variation of the classical Tur\'{a}n-type extremal problems. Let $S$ be an $n$-term graphical sequence, and $\sigma(S)$ be the sum of the terms in $S$. Let $H$ be a graph. The problem is to determine the smallest…

Combinatorics · Mathematics 2007-05-23 Chunhui Lai

A sequence of nonnegative integers \pi =(d_1,d_2,...,d_n) is graphic if there is a (simple) graph G with degree sequence \pi. In this case, G is said to realize or be a realization of \pi. Degree sequence results in the literature generally…

Combinatorics · Mathematics 2015-11-04 Michael Ferrara , Timothy D. LeSaulnier , Casey K. Moffatt , Paul S. Wenger

Let $K_k$, $C_k$, $T_k$, and $P_{k}$ denote a complete graph on $k$ vertices, a cycle on $k$ vertices, a tree on $k+1$ vertices, and a path on $k+1$ vertices, respectively. Let $K_{m}-H$ be the graph obtained from $K_{m}$ by removing the…

Combinatorics · Mathematics 2010-02-06 Chunhui Lai , Lili Hu

For given a graph $H$, a graphic sequence $\pi=(d_1,d_2,...,d_n)$ is said to be potentially $H$-graphic if there exists a realization of $\pi$ containing $H$ as a subgraph. Let $K_m-H$ be the graph obtained from $K_m$ by removing the edges…

Combinatorics · Mathematics 2009-01-13 Lili Hu , Chunhui Lai

The set of all non-increasing nonnegative integers sequence $\pi=$ ($d(v_1),$ $d(v_2),$ $...,$ $d(v_n)$) is denoted by $NS_n$. A sequence $\pi\in NS_n$ is said to be graphic if it is the degree sequence of a simple graph $G$ on $n$…

Combinatorics · Mathematics 2009-11-15 Chunhui Lai , Lili Hu

For given a graph $H$, a graphic sequence $\pi=(d_1,d_2,...,d_n)$ is said to be potentially $H$-graphic if there exists a realization of $\pi$ containing $H$ as a subgraph. Let $K_m-H$ be the graph obtained from $K_m$ by removing the edges…

Combinatorics · Mathematics 2009-07-10 Lili Hu , Chunhui Lai

A graph $G$ of order $n$ is said to be $k$-factor-critical for integers $1\leq k < n$, if the removal of any $k$ vertices results in a graph with a perfect matching. $1$- and $2$-factor-critical graphs are the well-known factor-critical and…

Combinatorics · Mathematics 2022-07-08 Jing Guo , Heping Zhang

A graph $G$ of order $n$ is said to be $k$-factor-critical for integers $1\leq k < n$, if the removal of any $k$ vertices results in a graph with a perfect matching. A $k$-factor-critical graph $G$ is called minimal if for any edge $e\in…

Combinatorics · Mathematics 2022-11-08 Jing Guo , Heping Zhang

For an integer sequence (with even sum), the closer that the sequence is to being regular, the more likely that the sequence is graphic. But how regular must a sequence be before it must always be graphic? We show that for many sequences if…

Combinatorics · Mathematics 2020-09-16 Brian Cloteaux

A fundamental theorem in graph theory states that any 3-connected graph contains a subdivision of $K_4$. As a generalization, we ask for the minimum number of $K_4$-subdivisions that are contained in every $3$-connected graph on $n$…

Discrete Mathematics · Computer Science 2015-06-16 Tillmann Miltzow , Jens M. Schmidt , Mingji Xia

Let $n_g(k)$ denote the smallest order of a $k$-chromatic graph of girth at least $g$. We consider the problem of determining $n_g(k)$ for small values of $k$ and $g$. After giving an overview of what is known about $n_g(k)$, we provide…

Combinatorics · Mathematics 2023-06-22 Geoffrey Exoo , Jan Goedgebeur

In this paper, we define the $4$-girth-thickness $\theta(4,G)$ of a graph $G$ as the minimum number of planar subgraphs of girth at least $4$ whose union is $G$. We obtain the $4$-girth-thickness of the arbitrary complete graph $K_n$…

Combinatorics · Mathematics 2018-10-03 Christian Rubio-Montiel

The codegree threshold $\mathrm{ex}_2(n, F)$ of a $3$-graph $F$ is the minimum $d=d(n)$ such that every $3$-graph on $n$ vertices in which every pair of vertices is contained in at least $d+1$ edges contains a copy of $F$ as a subgraph. We…

Combinatorics · Mathematics 2022-12-22 Victor Falgas-Ravry , Oleg Pikhurko , Emil R. Vaughan , Jan Volec
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