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In this paper we introduce compressed commuting graph of rings. It can be seen as a compression of the standard commuting graph (with the central elements added) where we identify the vertices that generate the same subring. The compression…

In this paper we introduce and study a class of tableaux which we call permutation tableaux; these tableaux are naturally in bijection with permutations, and they are a distinguished subset of the Le-diagrams of Alex Postnikov. The…

组合数学 · 数学 2007-05-23 Einar Steingrimsson , Lauren K. Williams

A signed graph has edge weights drawn from the set $\{+1,-1\}$, and is termed sign-balanced if it is equivalent to an unsigned graph under the operation of sign switching; otherwise it is called sign-unbalanced. A nut graph has a one…

组合数学 · 数学 2021-01-01 Nino Bašić , Patrick W. Fowler , Tomaž Pisanski , Irene Sciriha

Signed Graph Neural Networks (SGNNs) have been shown to be effective in analyzing complex patterns in real-world situations where positive and negative links coexist. However, SGNN models suffer from poor explainability, which limit their…

机器学习 · 计算机科学 2024-12-13 Lu Li , Jiale Liu , Xingyu Ji , Maojun Wang , Zeyu Zhang

We extend several results of the third author and C. Malvenuto on graph-different permutations to the case of directed graphs and introduce new open problems. Permutation capacity is a natural extension of Sperner capacity from finite…

组合数学 · 数学 2008-09-10 Gerard Cohen , Emanuela Fachini , Janos Korner

We give a bijective proof of an identity relating primed shifted gl(n)-standard tableaux to the product of a gl(n) character in the form of a Schur function and a product of sums of x and y terms. This result generalises a number of…

组合数学 · 数学 2007-05-23 A. M. Hamel , R. C. King

In this paper, various kinds of invariants of directed graphs are summarized. In the first topic, the invariant w(G) for a directed graph G is introduced, which is primarily defined by S. Chen and X.M. Chen to solve a problem of weak…

组合数学 · 数学 2015-01-16 Sheng Chen , Yilong Zhang

We present some corollaries to a symplectic primed shifted tableaux version of Tokuyama's identity expressed in terms of other combinatorial constructs, namely generalised $U$-turn alternating sign matrices and strict symplectic…

组合数学 · 数学 2015-10-01 Angèle M. Hamel , Ronald C. King

We generalize the work of Fomin, Greene, Reiner, and Shimozono on balanced labellings in two directions: (1) we define the diagrams of affine permutations and the balanced labellings on them; (2) we define the set-valued version of the…

组合数学 · 数学 2013-05-02 Hwanchul Yoo , Taedong Yun

The prevalence of graph-based data has spurred the rapid development of graph neural networks (GNNs) and related machine learning algorithms. Yet, despite the many datasets naturally modeled as directed graphs, including citation, website,…

机器学习 · 计算机科学 2021-06-14 Xitong Zhang , Yixuan He , Nathan Brugnone , Michael Perlmutter , Matthew Hirn

The emerging graph Transformers have achieved impressive performance for graph representation learning over graph neural networks (GNNs). In this work, we regard the self-attention mechanism, the core module of graph Transformers, as a…

机器学习 · 计算机科学 2023-10-18 Jinsong Chen , Gaichao Li , John E. Hopcroft , Kun He

The structure of order ideals in the Bruhat order for the symmetric group is elucidated via permutation patterns. A method for determining non-isomorphic principal order ideals is described and applied for small lengths. The permutations…

组合数学 · 数学 2007-05-23 Bridget Eileen Tenner

Tetravalent graphs admitting a half-arc-transitive subgroup of automorphisms, that is a subgroup acting transitively on its vertices and its edges but not on its arcs, are investigated. One of the most fruitful approaches for the study of…

组合数学 · 数学 2018-01-29 Alejandra Ramos Rivera , Primož Šparl

We introduce a new diagrammatic approach to perturbative quantum field theory, which we call flow-oriented perturbation theory (FOPT). Within it, Feynman graphs are replaced by strongly connected directed graphs (digraphs). FOPT is a…

高能物理 - 理论 · 物理学 2023-02-02 Michael Borinsky , Zeno Capatti , Eric Laenen , Alexandre Salas-Bernárdez

In this work, we refine recent results on the explicit construction of polynomial algebras associated with commutants of subalgebras in enveloping algebras of Lie algebras by considering an additional grading with respect to the subalgebra.…

Spectral characterizations of graphs is an important topic in spectral graph theory which has been studied extensively by researchers in recent years. The study of oriented graphs, however, has received less attention so far. In Qiu et…

组合数学 · 数学 2024-10-15 Yiquan Chao , Wei Wang , Hao Zhang

In this paper, we illustrate important aspects of the interplay between weighing matrices, $(v,k,\lambda)$-graphs with fixed-point free involutions, and signed graphs with an orthogonal adjacency matrix, which arises from thin divisible…

组合数学 · 数学 2025-12-19 Sergey Goryainov , Willem H. Haemers , Elena V. Konstantinova , Honghai Li

We study {\em sign-restricted matrices} (SRMs), a class of rectangular $(0, \pm 1)$-matrices generalizing the alternating sign matrices (ASMs). In an SRM each partial column sum, starting from row 1, equals 0 or 1, and each partial row sum,…

组合数学 · 数学 2021-01-13 Richard A. Brualdi , Geir Dahl

In the field of graph signal processing (GSP), directed graphs present a particular challenge for the "standard approaches" of GSP to due to their asymmetric nature. The presence of negative- or complex-weight directed edges, a graphical…

信号处理 · 电气工程与系统科学 2020-03-03 Kevin Schultz , Marisel Villafane-Delgado

In 2001, Davies, Gladwell, Leydold, and Stadler proved discrete nodal domain theorems for eigenfunctions of generalized Laplacians, i.e., symmetric matrices with non-positive off-diagonal entries. In this paper, we establish nodal domain…

谱理论 · 数学 2022-10-21 Chuanyuan Ge , Shiping Liu