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Let $G$ be a connected $n$-vertex graph in a proper minor-closed class $\mathcal G$. We prove that the extension complexity of the spanning tree polytope of $G$ is $O(n^{3/2})$. This improves on the $O(n^2)$ bounds following from the work…

Combinatorics · Mathematics 2021-12-21 Manuel Aprile , Samuel Fiorini , Tony Huynh , Gwenaël Joret , David R. Wood

We study a tree coloring model introduced by Guidon (2018), initially based on an analogy with a remote control system of a rail yard, seen as a switch tree. For a given rooted tree, we formalize the constraints on the coloring, in…

Discrete Mathematics · Computer Science 2024-05-28 Olivier Golinelli

A graph class $\mathcal{G}$ has linear growth if, for each graph $G \in \mathcal{G}$ and every positive integer $r$, every subgraph of $G$ with radius at most $r$ contains $O(r)$ vertices. In this paper, we show that every graph class with…

The rooted subtree prune and regraft (rSPR) distance between two rooted binary phylogenetic trees is a well-studied measure of topological dissimilarity that is NP-hard to compute. Here we describe an improved linear kernel for the problem.…

Data Structures and Algorithms · Computer Science 2023-08-21 Steven Kelk , Simone Linz , Ruben Meuwese

An edge-ordered graph is a graph with a total ordering of its edges. A path $P=v_1v_2\ldots v_k$ in an edge-ordered graph is called increasing if $(v_iv_{i+1}) > (v_{i+1}v_{i+2})$ for all $i = 1,\ldots,k-2$; it is called decreasing if…

Combinatorics · Mathematics 2020-01-22 Frank Duque , Ruy Fabila-Monroy , Carlos Hidalgo-Toscano , Pablo Pérez-Lantero

We describe a set of $\Delta -1$ slopes that are universal for 1-bend planar drawings of planar graphs of maximum degree $\Delta \geq 4$; this establishes a new upper bound of $\Delta-1$ on the 1-bend planar slope number. By universal we…

Computational Geometry · Computer Science 2017-03-14 Patrizio Angelini , Michael A. Bekos , Giuseppe Liotta , Fabrizio Montecchiani

Locally repairable codes (LRCs) are a class of codes designed for the local correction of erasures. They have received considerable attention in recent years due to their applications in distributed storage. Most existing results on LRCs do…

Information Theory · Computer Science 2015-11-24 Pengfei Huang , Eitan Yaakobi , Hironori Uchikawa , Paul H. Siegel

The edge-length ratio of a straight-line drawing of a graph is the ratio between the lengths of the longest and of the shortest edge in the drawing. The planar edge-length ratio of a planar graph is the minimum edge-length ratio of any…

Data Structures and Algorithms · Computer Science 2020-04-14 Manuel Borrazzo , Fabrizio Frati

In a directed graph $G$ with non-correlated edge lengths and costs, the \emph{network design problem with bounded distances} asks for a cost-minimal spanning subgraph subject to a length bound for all node pairs. We give a bi-criteria…

Data Structures and Algorithms · Computer Science 2014-09-24 Markus Chimani , Joachim Spoerhase

We present a new technique for proving logarithmic upper bounds for diameters of evolving random graph models, which is based on defining a coupling between random graphs and variants of random recursive trees. The advantage of the…

Discrete Mathematics · Computer Science 2014-10-24 Abbas Mehrabian

We prove that for every odd $q\geq 3$, any $q$-query binary, possibly non-linear locally decodable code ($q$-LDC) $E:\{\pm1\}^k \rightarrow \{\pm1\}^n$ must satisfy $k \leq \tilde{O}(n^{1-2/q})$. For even $q$, this bound was established in…

Computational Complexity · Computer Science 2024-11-22 Arpon Basu , Jun-Ting Hsieh , Pravesh K. Kothari , Andrew D. Lin

We develop a new family of linear programs, that yield upper bounds on the rate of binary linear codes of a given distance. Our bounds apply {\em only to linear codes.} Delsarte's LP is the weakest member of this family and our LP yields…

Information Theory · Computer Science 2022-11-16 Elyassaf Loyfer , Nati Linial

Arrangements of pseudolines are classic objects in discrete and computational geometry. They have been studied with increasing intensity since their introduction almost 100 years ago. The study of the number $B_n$ of non-isomorphic simple…

Combinatorics · Mathematics 2024-03-22 Fernando Cortés Kühnast , Justin Dallant , Stefan Felsner , Manfred Scheucher

One of the fundamental results in graph minor theory is that for every planar graph $H$, there is a minimum integer $f(H)$ such that graphs with no minor isomorphic to $H$ have treewidth at most $f(H)$. A lower bound for ${f(H)}$ can be…

Combinatorics · Mathematics 2026-01-16 J. Pascal Gollin , Kevin Hendrey , Sang-il Oum , Bruce Reed

By computations on generating functions, Szekeres proved in 1983 that the law of the diameter of a uniformly distributed rooted labelled tree with n vertices, rescaled by a factor n^{1/2} , converges to a distribution whose density is…

Probability · Mathematics 2015-03-18 Minmin Wang

We study straight-line drawings of planar graphs with few segments and few slopes. Optimal results are obtained for all trees. Tight bounds are obtained for outerplanar graphs, 2-trees, and planar 3-trees. We prove that every 3-connected…

Combinatorics · Mathematics 2008-09-09 Vida Dujmovic' , David Eppstein , Matthew Suderman , David R. Wood

Ge, Rusjan, and Zweifel (J. Stat. Phys. 59, 1265 (1990)) introduced a binary tree which represents all the periodic windows in the chaotic regime of iterated one-dimensional unimodal maps. We consider the scaling behavior in a modified tree…

chao-dyn · Physics 2009-10-22 Jukka A. Ketoja , Juhani Kurkijarvi

In 2001, Koml\'os, S\'ark\"ozy and Szemer\'edi proved that, for each $\alpha>0$, there is some $c>0$ and $n_0$ such that, if $n\geq n_0$, then every $n$-vertex graph with minimum degree at least $(1/2+\alpha)n$ contains a copy of every…

Combinatorics · Mathematics 2022-02-07 Amarja Kathapurkar , Richard Montgomery

Plane increasing trees are rooted labeled trees embedded into the plane such that the sequence of labels is increasing on any branch starting at the root. Relaxed binary trees are a subclass of unlabeled directed acyclic graphs. We…

Combinatorics · Mathematics 2018-07-12 Michael Wallner

Multiplication is one of the most fundamental computational problems, yet its true complexity remains elusive. The best known upper bound, by F\"{u}rer, shows that two $n$-bit numbers can be multiplied via a boolean circuit of size $O(n \lg…

Data Structures and Algorithms · Computer Science 2019-03-01 Peyman Afshani , Casper Benjamin Freksen , Lior Kamma , Kasper Green Larsen