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We characterize planar diagrams which may be divided into n arc embeddings in terms of their chord diagrams, generalizing a result of Taniyama for the case n = 2. Two algorithms are provided, one which finds a minimal arc embedding (in…

Geometric Topology · Mathematics 2010-11-02 Tobias Hagge

Two types of connected chord diagrams with chord endpoints lying in a collection of ordered and oriented real segments are considered here: the real segments may contain additional bivalent vertices in one model but not in the other. In the…

Combinatorics · Mathematics 2015-12-15 N. V. Alexeev , J. E. Andersen , R. C. Penner , P. G. Zograf

A chord diagram consists of a circle, called the backbone, with line segments, called chords, whose endpoints are attached to distinct points on the circle. The genus of a chord diagram is the genus of the orientable surface obtained by…

Geometric Topology · Mathematics 2016-04-15 Jonathan Burns , Nataša Jonoska , Masahico Saito

We introduce collages of string diagrams as a diagrammatic syntax for glueing multiple monoidal categories. Collages of string diagrams are interpreted as pointed bimodular profunctors. As the main examples of this technique, we introduce…

Category Theory · Mathematics 2023-12-15 Dylan Braithwaite , Mario Román

A long-standing conjecture of Thomassen says that every longest cycle of a $3$-connected graph has a chord. Thomassen (2018) proved that if $G$ is a $2$-connected cubic graph, then any longest cycle must have a chord. He also showed that in…

Combinatorics · Mathematics 2025-11-06 Haidong Wu , Shunzhe Zhang

We prove that the class of chordal graphs is easily testable in the following sense. There exists a constant $c>0$ such that, if adding/removing at most $\epsilon n^2$ edges to a graph $G$ with $n$ vertices does not make it chordal, then a…

Combinatorics · Mathematics 2019-02-19 Rémi de Joannis de Verclos

We enumerate chord diagrams without loops and without both loops and parallel chords. We show that the former ones describe Hamiltonian paths in $n$-dimensional octahedrons. The latter ones are also known as shapes. For labelled diagrams we…

Combinatorics · Mathematics 2017-09-18 Evgeniy Krasko , Alexander Omelchenko

To any generic curve in an oriented surface there corresponds an oriented chord diagram, and any oriented chord diagram may be realized by a curve in some oriented surface. The genus of an oriented chord diagram is the minimal genus of an…

Geometric Topology · Mathematics 2009-04-29 Nathan Linial , Tahl Nowik

Analytical expressions for the distribution of the length of chords corresponding to the affine invariant measure on the set of chords are given for convex polygons. These analytical expressions are a computational improvement over other…

Metric Geometry · Mathematics 2015-08-18 Ricardo García-Pelayo

A graphic arrangement is a subarrangement of the braid arrangement whose set of hyperplanes is determined by an undirected graph. A classical result due to Stanley, Edelman and Reiner states that a graphic arrangement is free if and only if…

Combinatorics · Mathematics 2025-05-21 Takuro Abe , Lukas Kühne , Paul Mücksch , Leonie Mühlherr

It is known that any chordal graph on $n$ vertices can be represented as the intersection of $n$ subtrees in a tree on $n$ nodes. This fact is recently used in [2] to generate random chordal graphs on $n$ vertices by generating $n$ subtrees…

Data Structures and Algorithms · Computer Science 2019-05-20 Tınaz Ekim , Mordechai Shalom , Oylum Şeker

We determine the number of nonequivalent chord diagrams of order $n$ under the action of two groups, $C_{2n}$, a cyclic group of order $2n$, and $D_{2n}$, a dihedral group of order $4n$. Asymptotic formulas are also established.

Combinatorics · Mathematics 2007-05-23 Andrei Khruzin

A graph is chordal if every cycle of length at least four contains a chord, that is, an edge connecting two nonconsecutive vertices of the cycle. Several classical applications in sparse linear systems, database management, computer vision,…

Data Structures and Algorithms · Computer Science 2016-12-07 David Bergman , Carlos H. Cardonha , Andre A. Cire , Arvind U. Raghunathan

We introduce nominal string diagrams as, string diagrams internal in the category of nominal sets. This requires us to take nominal sets as a monoidal category, not with the cartesian product, but with the separated product. To this end, we…

Logic in Computer Science · Computer Science 2019-04-17 Samuel Balco , Alexander Kurz

We introduce string diagrams for physical duoidal categories (normal $\otimes$-symmetric duoidal categories): they consist of string diagrams with wires forming a zigzag-free partial order and order-preserving nodes whose inputs and outputs…

Category Theory · Mathematics 2024-07-23 Mario Román

Rooted connected chord diagrams form a nice class of combinatorial objects. Recently they were shown to index solutions to certain Dyson-Schwinger equations in quantum field theory. Key to this indexing role are certain special chords which…

Combinatorics · Mathematics 2016-09-28 Julien Courtiel , Karen Yeats

A graph $G$ is said to be chordal if it has no induced cycles of length four or more. In a recent preprint Culbertson, Guralnik, and Stiller give a new characterization of chordal graphs in terms of sequences of what they call…

Combinatorics · Mathematics 2021-02-25 Anton Dochtermann

Chord diagrams on circles and their intersection graphs (also known as circle graphs) have been intensively studied, and have many applications to the study of knots and knot invariants, among others. However, chord diagrams on more general…

Combinatorics · Mathematics 2007-05-23 Thomas Fleming , Blake Mellor

This paper continues description of applications of signed chord length distribution started in part I (arXiv:0711.4734). It is shown simple relation between equation for some transfer integrals with source and target bodies and different…

Mathematical Physics · Physics 2010-05-11 Alexander Yu. Vlasov

The notion of a braided chord diagram is introduced and studied. An equivalence relation is given which identifies all braidings of a fixed chord diagram. It is shown that finite-type invariants are stratified by braid index for knots which…

Geometric Topology · Mathematics 2007-05-23 Joan S. Birman , Rolland Trapp