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We define integral odd Khovanov homology of principally unimodular bipartite graph-links.

Geometric Topology · Mathematics 2010-06-02 Igor Nikonov

The independence gap of a graph was introduced by Ekim et al. (2018) as a measure of how far a graph is from being well-covered. It is defined as the difference between the maximum and minimum size of a maximal independent set. We…

Combinatorics · Mathematics 2018-12-14 Tınaz Ekim , Didem Gözüpek , Ademir Hujdurović , Martin Milanič

We apply the techniques of totally twisted Khovanov homology to the constructions by M. Asaeda, J. Przytycki, and A. Sikora of Khovanov type homologies for links and tangles in I-bundles over (orientable) surfaces. As a result we describe…

Geometric Topology · Mathematics 2012-09-14 Nguyen D. Duong , Lawrence P. Roberts

This paper explores a particular statistical model on 6-valent graphs with special properties which turns out to be invariant with respect to certain Roseman moves if the graph is the singular point graph of a diagram of a 2-knot. The…

Mathematical Physics · Physics 2015-10-13 I. G. Korepanov , G. I. Sharygin , D. V. Talalaev

We introduce a new one-variable polynomial invariant of graphs, which we call the skew characteristic polynomial. For an oriented simple graph, this is just the characteristic polynomial of its anti-symmetric adjacency matrix. For…

Combinatorics · Mathematics 2024-02-14 R. Dogra , S. Lando

We define the independence ratio and the chromatic number for bounded, self-adjoint operators on an L^2-space by extending the definitions for the adjacency matrix of finite graphs. In analogy to the Hoffman bounds for finite graphs, we…

Functional Analysis · Mathematics 2014-10-07 Christine Bachoc , Evan DeCorte , Fernando Mario de Oliveira Filho , Frank Vallentin

We introduce a new graph polynomial that encodes interesting properties of graphs, for example, the number of matchings and the number of perfect matchings. Most importantly, for bipartite graphs the polynomial encodes the number of…

Discrete Mathematics · Computer Science 2010-02-10 Qi Ge , Daniel Stefankovic

We consider a certain class of simplicial complexes which includes the independence complexes of forests. We show that if a simplicial complex $K$ belongs to this class, then the polyhedral join $\mathcal{Z}^*_{K}(\underline{X}, \emptyset)$…

Combinatorics · Mathematics 2023-03-22 Kengo Okura

We show that edge-clique graphs of cocktail party graphs have unbounded rankwidth. This, and other observations lead us to conjecture that the edge-clique cover problem is NP-complete for cographs. We show that the independent set problem…

Combinatorics · Mathematics 2013-05-07 Ching-Hao Liu , Ton Kloks , Sheung-Hung Poon

We consider a family of distance graphs in $\mathbb{R}^n$ and find its independent numbers in some cases. Define graph $J_{\pm}(n,k,t)$ in the following way: the vertex set consists of all vectors from $\{-1,0,1\}^n$ with $k$ nonzero…

Combinatorics · Mathematics 2022-10-06 Danila Cherkashin , Sergei Kiselev

Vassiliev invariants can be studied by studying the spaces of chord diagrams associated with singular knots. To these chord diagrams are associated the intersection graphs of the chords. We extend results of Chmutov, Duzhin and Lando to…

Geometric Topology · Mathematics 2009-09-25 Blake Mellor

The independence polynomial of a graph is the generating polynomial for the number of independent sets of each size, and its roots are called {\em independence roots}. We investigate the stability of such polynomials, that is, conditions…

Combinatorics · Mathematics 2018-02-08 Jason Brown , Ben Cameron

To a digraph with a choice of certain integral basis, we construct a CW complex, whose integral singular cohomology is canonically isomorphic to the path cohomology of the digraph as introduced in \cite{GLMY}. The homotopy type of the CW…

Combinatorics · Mathematics 2014-09-23 An Huang , Shing-Tung Yau

In this paper, we investigate the complexity of Maximum Independent Set (MIS) in the class of $H$-free graphs, that is, graphs excluding a fixed graph as an induced subgraph. Given that the problem remains $NP$-hard for most graphs $H$, we…

Data Structures and Algorithms · Computer Science 2019-02-21 Édouard Bonnet , Nicolas Bousquet , Pierre Charbit , Stéphan Thomassé , Rémi Watrigant

We generalize two main theorems of matching polynomials of undirected simple graphs, namely, real-rootedness and the Heilmann-Lieb root bound. Viewing the matching polynomial of a graph $G$ as the independence polynomial of the line graph…

Combinatorics · Mathematics 2019-02-20 Jonathan Leake , Nick Ryder

We construct a cobordism group for embedded graphs in two different ways, first by using sequences of two basic operations, called "fusion" and "fission", which in terms of cobordisms correspond to the basic cobordisms obtained by attaching…

Algebraic Topology · Mathematics 2013-08-13 Ahmad Zainy Al-Yasry

The independence polynomial of a graph is the generating polynomial for the number of independent sets of each size. Two graphs are said to be \textit{independence equivalent} if they have equivalent independence polynomials. We extend…

Combinatorics · Mathematics 2018-10-15 Iain Beaton , Jason I. Brown , Ben Cameron

In this paper we consider the complex uniformly resolvable decompositions of the complete graph $K_v$ into subgraphs such that each resolution class contains only blocks isomorphic to the same graph from a given set $\mathcal H$. We…

Combinatorics · Mathematics 2020-03-24 Csilla Bujtàs , Mario Gionfriddo , Elena Guardo , Lorenzo Milazzo , Salvatore Milici , Zsolt Tuza

A link homology is defined that is independent of link diagrams. This diagramless homology is closely related to Khovanov homology.

Geometric Topology · Mathematics 2009-11-16 Adam McDougall

We show that there is an almost complex structure on a differential calculus on finite points coming from a bidirected finite graph without multiple edges or loops. We concentrate on a polygon as a concrete case. In particular, a…

Quantum Algebra · Mathematics 2024-06-07 Soumalya Joardar , Atibur Rahaman