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We study three aspects of commutation classes of reduced decompositions: the number of commutation classes, the structures of their corresponding graphs, and the enumeration of subnetworks, a concept recently introduced by Warrington [21].…

Combinatorics · Mathematics 2010-09-07 Delong Meng

In this paper we present a characterisation, by an infinite family of minimal forbidden induced subgraphs, of proper circular arc graphs which are intersection graphs of paths on a grid, where each path has at most one bend (turn).

Computational Geometry · Computer Science 2018-08-29 Esther Galby , Maria Pia Mazzoleni , Bernard Ries

We classify invariant curves for birational surface maps that are expanding on cohomology. When the expansion is exponential, the arithmetic genus of an invariant curve is at most one. This implies severe constraints on both the type and…

Algebraic Geometry · Mathematics 2007-05-23 Jeffrey Diller , Daniel Jackson , Andrew Sommese

In this paper, we compute the distributions of the statistic number of crossings over permutations avoiding one of the pairs $\{321,231\}$, $\{123,132\}$ and $\{123,213\}$. The obtained results are new combinatorial interpretations of two…

Combinatorics · Mathematics 2021-05-18 Paul M. Rakotomamonjy , Sandrataniaina R. Andriantsoa , Arthur Randrianarivony

We investigate permutations and involutions that avoid a pattern of length three and have a {\em unique} longest increasing subsequence.

Combinatorics · Mathematics 2020-03-25 Miklos Bona , Elijah DeJonge

We consider the distribution of ascents, descents, peaks, valleys, double ascents, and double descents over permutations avoiding a set of patterns. Many of these statistics have already been studied over sets of permutations avoiding a…

Combinatorics · Mathematics 2019-07-24 Michael Bukata , Ryan Kulwicki , Nicholas Lewandowski , Lara Pudwell , Jacob Roth , Teresa Wheeland

On one hand, we study the class of graphs on surfaces, satisfying tessellation properties, with positive Forman curvature on each edge. Via medial graphs, we provide a new proof for the finiteness of the class, and give a complete…

Combinatorics · Mathematics 2020-02-11 Yohji Akama , Bobo Hua , Yanhui Su , Haohang Zhang

We give the avoidance indices (morphic and antimorphic) for all unary patterns with involution.

Formal Languages and Automata Theory · Computer Science 2011-05-17 James D. Currie

A crossing-free morph is a continuous deformation between two graph drawings that preserves straight-line pairwise noncrossing edges. Motivated by applications in 3D morphing problems, we initiate the study of morphing graph drawings in the…

Computational Geometry · Computer Science 2026-01-21 Oksana Firman , Tim Hegemann , Boris Klemz , Felix Klesen , Marie Diana Sieper , Alexander Wolff , Johannes Zink

Permutations are usually enumerated by size, but new results can be found by enumerating them by inversions instead, in which case one must restrict one's attention to indecomposable permutations. In the style of the seminal paper by Simion…

Combinatorics · Mathematics 2025-05-28 Atli Fannar Franklín

We give some results about a bijection associating each permutation with a subexcedant function. This function is related to a particular decomposition of the permutation as a product of transpositions and therefore it has been called…

Combinatorics · Mathematics 2022-08-17 Fufa Beyene , Roberto Mantaci

We investigate the structure of graphs of twin-width at most $1$, and obtain the following results: - Graphs of twin-width at most $1$ are permutation graphs. In particular they have an intersection model and a linear structure. - There is…

Discrete Mathematics · Computer Science 2025-01-03 Jungho Ahn , Hugo Jacob , Noleen Köhler , Christophe Paul , Amadeus Reinald , Sebastian Wiederrecht

We prove the Bernoulli property for a class of counter-twisting linked twist maps. These compose orthogonal linear shears on the torus, orientated in the opposite sense to their co-twisting counterparts (where the shears reinforce one…

Dynamical Systems · Mathematics 2023-12-14 Joe Myers Hill

Modern methods of graph theory describe a graph up to isomorphism, which makes it difficult to create mathematical models for visualizing graph drawings on a plane. The topological drawing of the planar part of a graph allows representing…

Combinatorics · Mathematics 2024-08-01 Sergey Kurapov , Maxim Davidovsky

A permutation $\pi$ strongly avoids the pattern $\tau$ if both $\pi$ and $\pi^2$ avoid $\tau$. In this paper, we enumerate permutations of size $n$ that strongly avoid the pattern 132. This enumeration allows us to prove a conjecture that…

Combinatorics · Mathematics 2026-04-29 Kassie Archer , Christina Graves

We consider permutations avoiding a pattern of length three under the family of Mallows distributions. In particular, for any pattern $\tau\in S_3-\{321\}$, we obtain rather precise results on the asymptotic probability as $n\to\infty$ that…

Probability · Mathematics 2020-10-09 Ross G. Pinsky

We study the behaviour of random labelled and unlabelled cographs with n vertices as n tends to infinity. Our main result is a novel probabilistic limit in the space of graphons.

Probability · Mathematics 2019-06-26 Benedikt Stufler

In 2019, B\'ona and Smith introduced the notion of strong pattern avoidance, saying that a permutation $\pi$ strongly avoids a pattern $\sigma$ if $\pi$ and $\pi^2$ both avoid $\sigma$. Recently, Archer and Geary generalized the idea of…

Combinatorics · Mathematics 2024-05-07 Robin D. P. Zhou , Yongchun Zang

Inspired by a width invariant on permutations defined by Guillemot and Marx, Bonnet, Kim, Thomass\'e, and Watrigant introduced the twin-width of graphs, which is a parameter describing its structural complexity. This invariant has been…

Logic in Computer Science · Computer Science 2024-08-07 Édouard Bonnet , Jaroslav Nešetřil , Patrice Ossona de Mendez , Sebastian Siebertz , Stéphan Thomassé

The \emph{thinness} of a graph is a width parameter that generalizes some properties of interval graphs, which are exactly the graphs of thinness one. Graphs with thinness at most two include, for example, bipartite convex graphs. Many…

Discrete Mathematics · Computer Science 2023-10-06 Flavia Bonomo-Braberman , Gastón Abel Brito
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