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An odd coloring of a graph is a proper coloring such that every non-isolated vertex has a color that appears at an odd number of its neighbors. This notion was introduced by Petr\v{s}evski and \v{S}krekovski in 2022. In this paper, we focus…

Combinatorics · Mathematics 2025-04-30 Masaki Kashima , Kenta Ozeki

We enumerate cubic (3-regular) unicellular maps on closed surfaces up to all homeomorphisms. Using the orbifold approach, we reduce the unsensed enumeration to explicit counts of quotient maps and rooted cubic/precubic maps on simpler…

Combinatorics · Mathematics 2026-01-27 Alexander Omelchenko , Igor Labutin

We prove that finding a rooted subtree with at least $k$ leaves in a digraph is a fixed parameter tractable problem. A similar result holds for finding rooted spanning trees with many leaves in digraphs from a wide family $\cal L$ that…

Data Structures and Algorithms · Computer Science 2007-05-23 Noga Alon , Fedor Fomin , Gregory Gutin , Michael Krivelevich , Saket Saurabh

The binomial coefficients and Catalan triangle numbers appear as weight multiplicities of the finite-dimensional simple Lie algebras and affine Kac--Moody algebras. We prove that any binomial coefficient can be written as weighted sums…

Combinatorics · Mathematics 2017-10-18 Kyu-Hwan Lee , Se-jin Oh

We prove that the genus polynomials of the graphs called iterated claws are real-rooted. This continues our work directed toward the 25-year-old conjecture that the genus distribution of every graph is log-concave. We have previously…

Combinatorics · Mathematics 2015-01-27 J. L. Gross , T. Mansour , T. W. Tucker , D. G. L. Wang

A general class of stochastic Runge-Kutta methods for the weak approximation of It\^o and Stratonovich stochastic differential equations with a multi-dimensional Wiener process is introduced. Colored rooted trees are used to derive an…

Numerical Analysis · Mathematics 2013-10-24 Andreas Rößler

F-nomial coefficients encompass among others well-known binomial coefficients or Gaussian coefficients that count subsets of finite set and subspaces of finite vector space respectively. Here, the so called F-cobweb tiling sequences N(a)…

Combinatorics · Mathematics 2009-01-13 M. Dziemianczuk

The multi-species coalescent provides an elegant theoretical framework for estimating species trees and species demographics from genetic markers. Practical applications of the multi-species coalescent model are, however, limited by the…

Populations and Evolution · Quantitative Biology 2011-11-09 David Bryant , Remco Bouckaert , Joseph Felsenstein , Noah Rosenberg , Arindam RoyChoudhury

In this paper, we give a decomposition of triply rooted trees into three doubly rooted trees. This leads to a combinatorial interpretation of an identity conjectured by Lacasse in the study of the PAC-Bayesian machine learning theory, and…

Combinatorics · Mathematics 2013-01-01 William Y. C. Chen , Janet F. F. Peng , Harold R. L. Yang

Linearized polynomials appear in many different contexts, such as rank metric codes, cryptography and linear sets, and the main issue regards the characterization of the number of roots from their coefficients. Results of this type have…

Combinatorics · Mathematics 2020-05-07 Olga Polverino , Ferdinando Zullo

An and/or tree is usually a binary plane tree, with internal nodes labelled by logical connectives, and with leaves labelled by literals chosen in a fixed set of k variables and their negations. In the present paper, we introduce the first…

Combinatorics · Mathematics 2014-04-28 Antoine Genitrini , Cécile Mailler

We develop basic cluster theory from an elementary point of view using a variation of binary trees which we call mixed cobinary trees. We show that the number of isomorphism classes of such trees is given by the Catalan number Cn where n is…

Combinatorics · Mathematics 2013-08-12 Kiyoshi Igusa , Jonah Ostroff

We address the enumeration of properly q-colored planar maps, or more precisely, the enumeration of rooted planar maps M weighted by their chromatic polynomial \chi_M(q) and counted by the number of vertices and faces. We prove that the…

Combinatorics · Mathematics 2025-09-26 Olivier Bernardi , Mireille Bousquet-Mélou

The MULTICUT IN TREES problem consists in deciding, given a tree, a set of requests (i.e. paths in the tree) and an integer k, whether there exists a set of k edges cutting all the requests. This problem was shown to be FPT by Guo and…

Discrete Mathematics · Computer Science 2009-02-09 Nicolas Bousquet , Jean Daligault , Stephan Thomasse , Anders Yeo

In this article, we construct explicit examples of pairs of non-isomorphic trees with the same restricted $U$-polynomial for every $k$; by this we mean that the polynomials agree on terms with degree at most $k+1$. The main tool for this…

Combinatorics · Mathematics 2020-02-20 José Aliste-Prieto , Anna de Mier , José Zamora

Phylogenetic invariants are certain polynomials in the joint probability distribution of a Markov model on a phylogenetic tree. Such polynomials are of theoretical interest in the field of algebraic statistics and they are also of practical…

Populations and Evolution · Quantitative Biology 2008-01-21 Nicholas Eriksson

We define two symmetric $q,t$-Catalan polynomials in terms of the area and depth statistic and in terms of the dinv and dinv of depth statistics. We prove symmetry using an involution on plane trees. The same involution proves symmetry of…

Combinatorics · Mathematics 2022-08-12 Joseph Pappe , Digjoy Paul , Anne Schilling

This work addresses an enumeration problem on weighted bi-colored plane trees with prescribed vertex data, with all vertices labeled distinctly. We give a bijection proof of the enumeration formula originally due to Kochetkov, hence…

Combinatorics · Mathematics 2026-01-13 Sicheng Lu , Yi Song

We study the virial expansion of mixtures of countably many different types of particles. The main tool is the Lagrange-Good inversion formula, which has other applications such as counting coloured trees or studying probability generating…

Mathematical Physics · Physics 2014-06-24 Sabine Jansen , Stephen J. Tate , Dimitrios Tsagkarogiannis , Daniel Ueltschi

We introduce the notion of doubly rooted plane trees and give a decomposition of these trees, called the butterfly decomposition which turns out to have many applications. From the butterfly decomposition we obtain a one-to-one…

Combinatorics · Mathematics 2007-05-23 William Y. C. Chen , Nelson Y. Li , Louis W. Shapiro