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A total dominating set of a graph $G$ is a set $D$ of vertices of $G$ such that every vertex of $G$ has a neighbor in $D$. A locating-total dominating set of $G$ is a total dominating set $D$ of $G$ with the additional property that every…

Combinatorics · Mathematics 2016-07-25 Florent Foucaud , Michael A. Henning

We introduce a new subclass of chordal graphs that generalizes split graphs, which we call well-partitioned chordal graphs. Split graphs are graphs that admit a partition of the vertex set into cliques that can be arranged in a star…

Combinatorics · Mathematics 2020-02-26 Jungho Ahn , Lars Jaffke , O-joung Kwon , Paloma T. Lima

We show that the dominating set problem parameterized by solution size is fixed-parameter tractable (FPT) in graphs that do not contain the claw (K(1,3)), the complete bipartite graph on four vertices where the two parts have one and three…

Data Structures and Algorithms · Computer Science 2015-03-17 Marek Cygan , Geevarghese Philip , Marcin Pilipczuk , Michał Pilipczuk , Jakub Onufry Wojtaszczyk

An abstract topological graph (AT-graph) is a pair $A=(G,\mathcal{X})$, where $G=(V,E)$ is a graph and $\mathcal{X} \subseteq {E \choose 2}$ is a set of pairs of edges of $G$. A realization of $A$ is a drawing $\Gamma_A$ of $G$ in the plane…

Data Structures and Algorithms · Computer Science 2025-03-17 Giordano Da Lozzo , Walter Didimo , Fabrizio Montecchiani , Miriam Münch , Maurizio Patrignani , Ignaz Rutter

Let the Andr\'{a}sfai graph $\mathrm{And}_k$ be defined as the graph with vertex set $\{v_0,v_1,...c, v_{3k-2}\}$ and two vertices $v_i$ and $v_j$ being adjacent iff $|i-j| \equiv 1\mod 3$. The graphs $\mathrm{And}_k$ are maximal…

Combinatorics · Mathematics 2009-09-29 Peter Christian Heinig

The structure of all triangle free graphs G = (V,E) with |E| - 6|V| + 13\alpha(G) = 0 is determined, yielding an affirmative answer to a question of Stanis{\l}aw Radziszowski and Donald Kreher.

Combinatorics · Mathematics 2013-10-01 Jörgen Backelin

The random greedy algorithm for constructing a large partial Steiner-Triple-System is defined as follows. We begin with a complete graph on $n$ vertices and proceed to remove the edges of triangles one at a time, where each triangle removed…

Combinatorics · Mathematics 2010-04-15 Tom Bohman , Alan Frieze , Eyal Lubetzky

A temporal graph is a graph in which connections between vertices are active at specific times, and such temporal information leads to completely new patterns and knowledge that are not present in a non-temporal graph. In this paper, we…

Data Structures and Algorithms · Computer Science 2014-01-10 Silu Huang , James Cheng , Huanhuan Wu

For $k \geq 3$, we prove (i) there is a finite number of $k$-vertex-critical $(P_2+\ell P_1)$-free graphs and (ii) $k$-vertex-critical $(P_3+P_1)$-free graphs have at most $2k-1$ vertices. Together with previous research, these results…

Combinatorics · Mathematics 2020-07-02 Ben Cameron , Chính T. Hoàng , Joe Sawada

We define specific multiplicities on the braid arrangement by using edge-bicolored graphs. To consider their freeness, we introduce the notion of bicolor-eliminable graphs as a generalization of Stanley's classification theory of free…

Commutative Algebra · Mathematics 2017-08-01 Takuro Abe , Koji Nuida , Yasuhide Numata

Ajtai, Koml\'os, and Szemer\'edi proved that for sufficiently large $t$ every triangle-free graph with $n$ vertices and average degree $t$ has an independent set of size at least $\frac{n}{100t}\log{t}$. We extend this by proving that the…

Combinatorics · Mathematics 2011-11-17 Jeff Cooper , Dhruv Mubayi

Alon, Krivelevich, and Sudakov conjectured in 1999 that every $F$-free graph of maximum degree at most $\Delta$ has chromatic number $O(\Delta / \log \Delta)$. This was previously known only for almost bipartite graphs, that is, for…

Combinatorics · Mathematics 2025-12-05 Abhishek Dhawan , Oliver Janzer , Abhishek Methuku

A graph is \emph{fan-crossing free} if it has a drawing in the plane so that each edge is crossed by independent edges, that is the crossing edges have distinct vertices. On the other hand, it is \emph{fan-crossing} if the crossing edges…

Discrete Mathematics · Computer Science 2020-12-14 Franz J. Brandenburg

A diamond is the graph that is obtained from removing an edge from the complete graph on $4$ vertices. A ($C_4$,diamond)-free graph is a graph that does not contain a diamond or a cycle on four vertices as induced subgraphs. Let $G$ be a…

Combinatorics · Mathematics 2022-08-01 Ruy Fabila-Monroy , Ana Laura Trujillo-Negrete

Read-only memory model is a classical model of computation to study time-space tradeoffs of algorithms. One of the classical results on the ROM model is that any sorting algorithm that uses O(s) words of extra space requires $\Omega…

Data Structures and Algorithms · Computer Science 2017-11-28 Sankardeep Chakraborty , Anish Mukherjee , Venkatesh Raman , Srinivasa Rao Satti

A vertex set $D$ in a finite undirected graph $G$ is an efficient dominating set (e.d.s. for short) of $G$ if every vertex of $G$ is dominated by exactly one vertex of $D$. The Efficient Domination (ED) problem, which asks for the existence…

Discrete Mathematics · Computer Science 2019-05-01 Andreas Brandstädt , Raffaele Mosca

It is shown that if the binomial edge ideal of a graph $G$ defines a Koszul algebra, then $G$ must be chordal and claw free. A converse of this statement is proved for a class of chordal and claw free graphs.

Commutative Algebra · Mathematics 2013-10-25 Viviana Ene , Jürgen Herzog , Takayuki Hibi

This is the second in a series of two papers dealing with $(2P_3,C_4,C_6)$-free graphs, or equivalently, $(2P_3,\text{even hole})$-free graphs. In this two-paper series, we give a full structural description of $(2P_3,C_4,C_6)$-free graphs…

Combinatorics · Mathematics 2025-11-17 Irena Penev

A $k$-bend path is a non-self-intersecting polyline in the plane made of at most $k+1$ axis-parallel line segments. B$_k$-VPG is the class of graphs which can be represented as intersection graphs of $k$-bend paths in the same plane. In…

Combinatorics · Mathematics 2023-03-07 Sparsh Jain , Sreejith K. Pallathumadam , Deepak Rajendraprasad

A graph $G$ is $1$-extendible if every edge belongs to at least one $1$-factor of $G$. Let $G$ be a graph with a $1$-factor $F$. Then an even $F$-orientation of $G$ is an orientation in which each $F$-alternating cycle has exactly an even…

Combinatorics · Mathematics 2024-03-20 M. Abreu , D. Labbate , F. Romaniello , J. Sheehan
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