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A graph $G=(V,E)$ is a $k$-leaf power if there is a tree $T$ whose leaves are the vertices of $G$ with the property that a pair of leaves $u$ and $v$ induce an edge in $G$ if and only if they are distance at most $k$ apart in $T$. For $k\le…

Combinatorics · Mathematics 2024-07-03 Max Dupré la Tour , Manuel Lafond , Ndiamé Ndiaye , Adrian Vetta

A common task in phylogenetics is to find an evolutionary tree representing proximity relationships between species. This motivates the notion of leaf powers: a graph G = (V, E) is a leaf power if there exist a tree T on leafset V and a…

Discrete Mathematics · Computer Science 2017-07-04 Manuel Lafond

Motivated by the problem of reconstructing evolutionary history, Nishimura et al. defined $k$-leaf powers as the class of graphs $G=(V,E)$ which has a $k$-leaf root $T$, i.e., $T$ is a tree such that the vertices of $G$ are exactly the…

Combinatorics · Mathematics 2009-09-25 Xueliang Li , Yongtang Shi , Wenli Zhou

A strong clique in a graph is a clique intersecting every maximal independent set. We study the computational complexity of six algorithmic decision problems related to strong cliques in graphs and almost completely determine their…

Combinatorics · Mathematics 2018-08-28 Ademir Hujdurović , Martin Milanič , Bernard Ries

A graph $G$ is a $k$-leaf power if there exists a tree $T$ whose leaf set is $V(G)$, and such that $uv \in E(G)$ if and only if the distance between $u$ and $v$ in $T$ is at most $k$. The graph classes of $k$-leaf powers have several…

Data Structures and Algorithms · Computer Science 2021-11-01 Manuel Lafond

The boxicity of a graph G, denoted as box(G) is defined as the minimum integer t such that G is an intersection graph of axis-parallel t-dimensional boxes. A graph G is a k-leaf power if there exists a tree T such that the leaves of the…

Combinatorics · Mathematics 2009-02-23 L. Sunil Chandran , Mathew C. Francis , Rogers Mathew

A graph is a $k$-leaf power of a tree $T$ if its vertices are leaves of $T$ and two vertices are adjacent in $T$ if and only if their distance in $T$ is at most $k$. Then $T$ is a $k$-leaf root of $G$. This notion was introduced by…

Discrete Mathematics · Computer Science 2015-03-17 Michel Habib , Thu-Hien To

A graph is locally chordal if each of its small-radius balls is chordal. In an earlier work [AKK25], the authors and Kobler proved that locally chordal graphs can be characterized by having chordal local covers, by forbidding short cycles…

Combinatorics · Mathematics 2025-12-23 Tara Abrishami , Paul Knappe

A graph G is a k-leaf power, for an integer k >= 2, if there is a tree T with leaf set V(G) such that, for all vertices x, y in V(G), the edge xy exists in G if and only if the distance between x and y in T is at most k. Such a tree T is…

Combinatorics · Mathematics 2023-08-22 Van Bang Le , Christian Rosenke

A proper vertex coloring of a graph is a mapping of its vertices on a set of colors, such that two adjacent vertices are not mapped to the same color. This constraint may be interpreted in terms of the distance between to vertices and so a…

Combinatorics · Mathematics 2017-11-10 Sebastian Wiederrecht

A $k$-leaf power of a tree $T$ is a graph $G$ whose vertices are the leaves of $T$ and whose edges connect pairs of leaves whose distance in $T$ is at most $k$. A graph is a leaf power if it is a $k$-leaf power for some $k$. Over 20 years…

Data Structures and Algorithms · Computer Science 2022-03-10 Benjamin Bergougnoux , Svein Høgemo , Jan Arne Telle , Martin Vatshelle

Given a root system $R$, two roots are said to be \emph{strongly orthogonal} if neither their sum nor difference is a root. Gashi defined a family of graphs with vertices labelled by sums of $k$-element strongly orthogonal subsets of roots,…

Combinatorics · Mathematics 2026-04-06 Patrick J. Browne , Pádraig Ó Catháin

The $k$th power of a graph $G$, denoted $G^k$, has the same vertex set as $G$, and two vertices are adjacent in $G^k$ if and only if there exists a path between them in $G$ of length at most $k$. A $K_r$-factor in a graph is a spanning…

Combinatorics · Mathematics 2022-11-29 Ajit Diwan , Aniruddha Joshi

Galinier, Habib, and Paul introduced the reduced clique graph of a chordal graph $G$. The nodes of the reduced clique graph are the maximal cliques of $G$, and two nodes are joined by an edge if and only if they form a non-disjoint…

Combinatorics · Mathematics 2024-04-15 Dillon Mayhew , Andrew Probert

For integer $k\geq2,$ a graph $G$ is called $k$-leaf-connected if $|V(G)|\geq k+1$ and given any subset $S\subseteq V(G)$ with $|S|=k,$ $G$ always has a spanning tree $T$ such that $S$ is precisely the set of leaves of $T.$ Thus a graph is…

Combinatorics · Mathematics 2022-11-10 Tingyan Ma , Guoyan Ao , Ruifang Liu , Ligong Wang , Yang Hu

We initiate the study of graph classes of power-bounded clique-width, that is, graph classes for which there exist integers $k$ and $\ell$ such that the $k$-th powers of the graphs are of clique-width at most $\ell$. We give sufficient and…

Combinatorics · Mathematics 2023-04-04 Flavia Bonomo , Luciano N. Grippo , Martin Milanič , Martín D. Safe

The $k^{th}$-power of a given graph $G=(V,E)$ is obtained from $G$ by adding an edge between every two distinct vertices at a distance at most $k$ in $G$. We call $G$ a $k$-Steiner power if it is an induced subgraph of the $k^{th}$-power of…

Computational Complexity · Computer Science 2019-02-05 Guillaume Ducoffe

We present a new characterization of $k$-trees based on their reduced clique graphs and $(k+1)$-line graphs, which are block graphs. We explore structural properties of these two classes, showing that the number of clique-trees of a…

Combinatorics · Mathematics 2026-02-17 Lilian Markenzon , Allana S. S. Oliveira , Cybele T. M. Vinagre

The leafage l(G) of a chordal graph G is the minimum number of leaves of a tree in which G has an intersection representation by subtrees. We obtain upper and lower bounds on l(G) and compute it on special classes. The maximum of l(G) on…

Combinatorics · Mathematics 2007-05-23 In-Jen Lin , Terry A. McKee , Douglas B. West

The power graph $\mathcal{P}(G)$ of a finite group $G$ is the graph whose vertex set is $G$, and two elements in $G$ are adjacent if one of them is a power of the other. The purpose of this paper is twofold. First, we find the complexity of…

Group Theory · Mathematics 2018-06-07 S. Kirkland , A. R. Moghaddamfar , S. Navid Salehy , S. Nima Salehy , M. Zohourattar
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