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In this paper, we study the staircase encoding of permutations, which maps a permutation to a staircase grid with cells filled with permutations. We consider many cases, where restricted to a permutation class, the staircase encoding…

Combinatorics · Mathematics 2023-06-22 Christian Bean , Émile Nadeau , Henning Ulfarsson

We define the \emph{occurrence graph} $G_p(\pi$) of a pattern $p$ in a permutation $\pi$ as the graph with the occurrences of $p$ in $\pi$ as vertices and edges between the vertices if the occurrences differ by exactly one element. We then…

Combinatorics · Mathematics 2019-08-14 Bjarni Jens Kristinsson , Henning Ulfarsson

We strengthen and put in a broader perspective previous results of the first two authors on colliding permutations. The key to the present approach is a new non-asymptotic invariant for graphs.

Combinatorics · Mathematics 2007-09-28 János Körner , Claudia Malvenuto , Gábor Simonyi

Graphs arise naturally in many real-world applications including social networks, recommender systems, ontologies, biology, and computational finance. Traditionally, machine learning models for graphs have been mostly designed for static…

Machine Learning · Computer Science 2020-04-28 Seyed Mehran Kazemi , Rishab Goel , Kshitij Jain , Ivan Kobyzev , Akshay Sethi , Peter Forsyth , Pascal Poupart

We study a class of complex polynomial equations on a finite graph with a view to understanding how holistic phenomena emerge from combinatorial structure. Particular solutions arise from orthogonal projections of regular polytopes,…

Mathematical Physics · Physics 2011-09-16 Paul Baird

We introduce orbital graphs and discuss some of their basic properties. Then we focus on their usefulness for search algorithms for permutation groups, including finding the intersection of groups and the stabilizer of sets in a group.

Group Theory · Mathematics 2017-05-24 Paula Hähndel , Christopher Jefferson , Markus Pfeiffer , Rebecca Waldecker

For a graph with edge ordering, a linear order on the edge set, we obtain a permutation of vertices by considering the edges as transpositions of endvertices. It is known from D\'enes' results that the permutation of a tree is a full cyclic…

Combinatorics · Mathematics 2023-05-31 Ryo Uchiumi

Graphs derived from groups are a widely studied class of graphs, motivated by their highly symmetric structure. In particular, G-graphs offer an easy and interesting alternative construction of semi-symmetric graphs. After recalling the…

Combinatorics · Mathematics 2016-11-25 David Ellison , Ruxandra Marinescu-Ghemeci , Cerasela Tanasescu

In this paper, we reveal an intriguing relationship between two seemingly unrelated notions: letter graphs and geometric grid classes of permutations. An important property common for both of them is well-quasi-orderability, implying, in a…

Combinatorics · Mathematics 2018-05-01 Bogdan Alecu , Vadim Lozin , Dominique de Werra , Viktor Zamaraev

In this paper we discuss graph inverse semigroups which are constucted from a directed graphs and study several interesting properties of graph inverse semigroups such as the nature of its idempotents, the structure of semilattice of…

Group Theory · Mathematics 2020-04-07 P G Romeo , Alanka Thomas

A generic method for combinatorial constructions of intrinsic geometrical spaces is presented. It is based on the well known inverse sequences of finite graphs that determine (in the limit) topological spaces. If a pattern of the…

Computational Geometry · Computer Science 2020-10-09 Stanislaw Ambroszkiewicz

Let $G$ be a graph and $A$ be its adjacency matrix. A graph $G$ is invertible if its adjacency matrix $A$ is invertible and the inverse of $G$ is a weighted graph with adjacency matrix $A^{-1}$. A signed graph $(G,\sigma)$ is a weighted…

Combinatorics · Mathematics 2023-03-23 Isaiah Osborne , Dong Ye

The present work is concerned with characterizing some algebraic invariants of edge ideals of hypergraphs. To this aim, firstly, we introduce some kinds of combinatorial invariants similar to matching numbers for hypergraphs. Then we…

Commutative Algebra · Mathematics 2025-06-10 Somayeh Moradi , Fahimeh Khosh-Ahang Ghasr

For a representation of a Lie algebra, one can construct a diagram of the representation, i. e. a directed graph with edges labeled by matrix elements of the representation. This article explains how to use these diagrams to describe normal…

Representation Theory · Mathematics 2007-05-23 Aleksandrs Mihailovs

We introduce an algorithm that conjectures the structure of a permutation class in the form of a disjoint cover of "rules"; similar to generalized grid classes. The cover is usually easily verified by a human and translated into an…

Combinatorics · Mathematics 2017-05-12 Christian Bean , Bjarki Gudmundsson , Henning Ulfarsson

Neural networks that process the parameters of other neural networks find applications in domains as diverse as classifying implicit neural representations, generating neural network weights, and predicting generalization errors. However,…

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 study finite graphs embedded in oriented surfaces by associating a polynomial to it. The tools used in developing a theory of such graph polynomials are algebraic topological while the polynomial itself is inspired from ideas arising in…

Combinatorics · Mathematics 2022-05-02 Somnath Basu , Dhruv Bhasin , Siddhartha Lal , Siddhartha Patra

The problem of finding graph structure of functions commuting with a given function in terms of their functional graphs is considered. Structure of functional graphs of commuting functions is described. The problem is reduced to describing…

Combinatorics · Mathematics 2015-01-05 Peteris Daugulis

By natural way the hierarchy structure is introduced on directed graphs with weighted adjacencies. Embedded system of algebras of subsets of the set of vertices of such digraph and it's consolidations, which vertices are the elementary sets…

Combinatorics · Mathematics 2007-05-23 V. A. Buslov