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We study the problem of gradually representing a complex graph as a sequence of drawings of small subgraphs whose union is the complex graph. The sequence of drawings is called \emph{storyplan}, and each drawing in the sequence is called a…

Computational Geometry · Computer Science 2025-10-02 Jiří Fiala , Oksana Firman , Giuseppe Liotta , Alexander Wolff , Johannes Zink

We consider sequences of finitely generated discrete subgroups Gamma_i=rho_i(Gamma) of a rank 1 Lie group G, where the representations rho_i are not necessarily faithful. We show that, for algebraically convergent sequences (Gamma_i),…

Group Theory · Mathematics 2007-08-21 Michael Kapovich

We obtain analogues of classical results on automorphism groups of holomorphic fiber bundles, in the setting of group schemes. Also, we establish a lifting property of the connected automorphism group, for torsors under abelian varieties.…

Algebraic Geometry · Mathematics 2011-06-30 Michel Brion

We prove a tropical analogue of the theorem of Hurwitz: a leafless metric graph of genus $g \ge 2$ has at most $12$ automorphisms when $g = 2$; $2^g g!$ automorphisms when $g \ge 3$. These inequalities are optimal; for each genus, we give…

Combinatorics · Mathematics 2021-10-13 Yusuke Nakamura , JuAe Song

The spectrum of the $k$-power hypergraph of a graph $G$ is called the $k$-ordered spectrum of $G$.If graphs $G_1$ and $G_2$ have same $k$-ordered spectrum for all positive integer $k\geq2$, $G_1$ and $G_2$ are said to be high-ordered…

Combinatorics · Mathematics 2021-11-09 Lixiang Chen , Lizhu Sun , Changjiang Bu

For a graph $G = (V, E)$, the $\gamma$-graph of $G$, denoted $G(\gamma) = (V(\gamma), E(\gamma))$, is the graph whose vertex set is the collection of minimum dominating sets, or $\gamma$-sets of $G$, and two $\gamma$-sets are adjacent in…

Combinatorics · Mathematics 2019-07-31 Stephen Finbow , Christopher M. van Bommel

In this paper we resolve the complexity of the isomorphism problem on all but finitely many of the graph classes characterized by two forbidden induced subgraphs. To this end we develop new techniques applicable for the structural and…

Discrete Mathematics · Computer Science 2014-11-10 Pascal Schweitzer

In this paper, we study the discrete differential calculus on hypergraphs by using the Kouzul complexes. We define the constrained (co)homology for hypergraphs and give the corresponding Mayer-Vietoris sequences. We prove the functoriality…

Algebraic Topology · Mathematics 2023-10-24 Shiquan Ren

The transmission of a vertex in a connected graph is the sum of distances from that vertex to all the other vertices. A connected graph is transmission irregular if any two distinct vertices have different transmissions. We present an…

Discrete Mathematics · Computer Science 2026-02-20 Ivan Stošić , Ivan Damnjanović

We discuss the relationship between (co)homology groups and categorical diagonalization. We consider the category of chain complexes in the category of finitely generated free modules on a commutative ring. For a fixed chain complex with…

Category Theory · Mathematics 2021-01-06 Jumpei Gohara , Yuji Hirota , Keisui Ino , Akifumi Sako

We calculate the rational cohomology of the classifying space of the diffeomorphism group of the manifolds $U_{g,1}^n:= \#^g(S^n \times S^{n+1})\setminus \mathrm{int}{D^{2n+1}}$, for large $g$ and $n$, up to approximately degree $n$. The…

Algebraic Topology · Mathematics 2024-02-21 Johannes Ebert , Jens Reinhold

We introduce the notion of \emph{bounded diameter arboricity}. Specifically, the \emph{diameter-$d$ arboricity} of a graph is the minimum number $k$ such that the edges of the graph can be partitioned into $k$ forests each of whose…

Combinatorics · Mathematics 2016-08-19 Martin Merker , Luke Postle

Cheeger-Simons differential characters, Deligne cohomology in the smooth category, the Hopkins-Singer construction of ordinary differential cohomology and the recent Harvey-Lawson constructions are each in two distinct ways Abelian group…

Algebraic Topology · Mathematics 2014-02-26 James Simons , Dennis Sullivan

An orthogonal Haar scattering transform is a deep network, computed with a hierarchy of additions, subtractions and absolute values, over pairs of coefficients. It provides a simple mathematical model for unsupervised deep network learning.…

Machine Learning · Computer Science 2015-10-01 Xiuyuan Cheng , Xu Chen , Stephane Mallat

Many important graph theoretic notions can be encoded as counting graph homomorphism problems, such as partition functions in statistical physics, in particular, independent sets and colourings. In this article we study the complexity of…

Computational Complexity · Computer Science 2018-04-24 Andreas Göbel , J. A. Gregor Lagodzinski , Karen Seidel

For graphs $G$ and $H$, a \emph{homomorphism} from $G$ to $H$ is an edge-preserving mapping from the vertex set of $G$ to the vertex set of $H$. For a fixed graph $H$, by \textsc{Hom($H$)} we denote the computational problem which asks…

Computational Complexity · Computer Science 2020-02-20 Karolina Okrasa , Paweł Rzążewski

This work provides a structural characterisation of hereditary graph classes that do not contain a star forest, several graphs obtained from star forests by subset complementation, a union of cliques, and the complement of a union of…

Combinatorics · Mathematics 2017-11-09 Aistis Atminas

Cospectral graphs are a fascinating concept in graph theory, where two non-isomorphic graphs possess identical sets of eigenvalues. In this paper, we compute the $A_\alpha$-characteristic polynomial of neighbour and non-neighbour splitting…

Combinatorics · Mathematics 2024-03-11 Najiya V K , Chithra A

We consider the classical problems (Edge) Steiner Tree and Vertex Steiner Tree after restricting the input to some class of graphs characterized by a small set of forbidden induced subgraphs. We show a dichotomy for the former problem…

Data Structures and Algorithms · Computer Science 2020-12-17 Hans Bodlaender , Nick Brettell , Matthew Johnson , Giacomo Paesani , Daniel Paulusma , Erik Jan van Leeuwen

In a recent paper [3], the authors introduced a map $\mathcal{F}$ which associates a Deitmar scheme (which is defined over the field with one element, denoted by $\mathbb{F}_1$) with any given graph $\Gamma$. By base extension, a scheme…

Algebraic Geometry · Mathematics 2016-05-10 Manuel Merida-Angulo , Koen Thas
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