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In analogy to a concept of Fibonacci trees, we define the leaf-Fibonacci tree of size $n$ and investigate its number of nonisomorphic leaf-induced subtrees. Denote by $f_0$ the one vertex tree and $f_1$ the tree that consists of a root with…

Combinatorics · Mathematics 2018-11-16 Audace Amen Vioutou Dossou-Olory

This paper studies the differential lattice, defined to be a lattice $L$ equipped with a map $d:L\to L$ that satisfies a lattice analog of the Leibniz rule for a derivation. Isomorphic differential lattices are studied and classifications…

Rings and Algebras · Mathematics 2021-06-17 Aiping Gan , Li Guo

An evolutionary tree is a rooted tree where each internal vertex has at least two children and where the leaves are labeled with distinct symbols representing species. Evolutionary trees are useful for modeling the evolutionary history of…

Computational Engineering, Finance, and Science · Computer Science 2007-05-23 Ming-Yang Kao

Every chordal graph $G$ can be represented as the intersection graph of a collection of subtrees of a host tree, a so-called {\em tree model} of $G$. The leafage $\ell(G)$ of a connected chordal graph $G$ is the minimum number of leaves of…

Discrete Mathematics · Computer Science 2015-10-07 Steven Chaplick , Juraj Stacho

The rank (also known as protection number or leaf-height) of a vertex in a rooted tree is the minimum distance between the vertex and any of its leaf descendants. We consider the sum of ranks over all vertices (known as the security) in…

Minimum Bisection denotes the NP-hard problem to partition the vertex set of a graph into two sets of equal sizes while minimizing the width of the bisection, which is defined as the number of edges between these two sets. We first consider…

Combinatorics · Mathematics 2017-08-23 Cristina G. Fernandes , Tina Janne Schmidt , Anusch Taraz

In this paper, we propose an algorithm to generate all possible graceful graphs (including trees) containing n vertices as lattice paths in a certain triangular lattice defined below. This lattice that corresponds to graphs containing n…

General Mathematics · Mathematics 2024-03-22 Dhananjay P. Mehendale

The "separation dimension" of a graph $G$ is the minimum positive integer $d$ for which there is an embedding of $G$ into $\mathbb{R}^d$, such that every pair of disjoint edges are separated by some axis-parallel hyperplane. We prove a…

Combinatorics · Mathematics 2021-07-01 Alex Scott , David R. Wood

Let $k$ and $n$ be integers such that $1\leq k \leq n-1$, and let $G$ be a simple graph of order $n$. The $k$-token graph $F_k(G)$ of $G$ is the graph whose vertices are the $k$-subsets of $V(G)$, where two vertices are adjacent in $F_k(G)$…

Combinatorics · Mathematics 2023-06-22 Ruy Fabila-Monroy , Jesús Leaños , Ana Laura Trujillo-Negrete

A set of vertices $W$ resolves a graph $G$ if every vertex is uniquely determined by its vector of distances to the vertices in $W$. A metric dimension of $G$ is the minimum cardinality of a resolving set of $G$. A bipartite graph G(n,n) is…

Combinatorics · Mathematics 2015-03-17 S. W. Saputro , E. T. Baskoro , A. N. M. Salman , D. Suprijanto , And M. Baca

An L-shaped embedding of a tree in a point set is a planar drawing of the tree where the vertices are mapped to distinct points and every edge is drawn as a sequence of two axis-aligned line segments. There has been considerable work on…

Computational Geometry · Computer Science 2020-05-01 Torsten Mütze , Manfred Scheucher

We give an $O(g^{1/2} n^{3/2} + g^{3/2} n^{1/2})$-size extended formulation for the spanning tree polytope of an $n$-vertex graph embedded on a surface of genus $g$, improving on the known $O(n^2 + g n)$-size extended formulations following…

Combinatorics · Mathematics 2017-03-03 Samuel Fiorini , Tony Huynh , Gwenaël Joret , Kanstantsin Pashkovich

While the notion of arboricity of a graph is well-known in graph theory, very few results are dedicated to the minimal number of trees covering the edges of a graph, called the tree number of a graph.

Discrete Mathematics · Computer Science 2020-08-03 Natalia Vanetik

A higher dimensional lattice space can be decomposed into a number of four-dimensional lattices called as layers. The higher dimensional gauge theory on the lattice can be interpreted as four-dimensional gauge theories on the multi-layer…

High Energy Physics - Lattice · Physics 2009-11-10 M. Murata , H. So

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

Let $G$ be a graph on $n$ vertices and $1 \le k \le n$ a fixed integer. The \textit{$k$-token graph} of $G$ is the graph $F_k(G)$ whose vertex set consists of all $k$-subsets of the vertex set of $G$, where two vertices $A$ and $B$ are…

We prove that every graph of rank-width $k$ is a pivot-minor of a graph of tree-width at most $2k$. We also prove that graphs of rank-width at most 1, equivalently distance-hereditary graphs, are exactly vertex-minors of trees, and graphs…

Combinatorics · Mathematics 2014-03-26 O-joung Kwon , Sang-il Oum

We present the Boolean dimension of a graph, we relate it with the notions of inner, geometric and symplectic dimensions, and with the rank and minrank of a graph. We obtain an exact formula for the Boolean dimension of a tree in terms of a…

Combinatorics · Mathematics 2022-09-07 Maurice Pouzet , Hamza Si Kaddour , Bhalchandra D. Thatte

Given an ordered partition $\Pi =\{P_1,P_2, ...,P_t\}$ of the vertex set $V$ of a connected graph $G=(V,E)$, the \emph{partition representation} of a vertex $v\in V$ with respect to the partition $\Pi$ is the vector…

Combinatorics · Mathematics 2014-02-10 Juan A. Rodriguez-Velazquez , Ismael G. Yero , Magdalena Lemanska

A graph has tree-width at most $k$ if it can be obtained from a set of graphs each with at most $k+1$ vertices by a sequence of clique sums. We refine this definition by, for each non-negative integer $\theta$, defining the…

Combinatorics · Mathematics 2016-09-30 Jim Geelen , Benson Joeris