University of West Bohemia in Pilsen

output

20042026

most citedSciPy 1.0--Fundamental Algorithms for Scientific Computing in Python

40.2k citations

researchers with a paper here

Counting papers with at most 25 authors, so collaboration author lists do not stand in for the people here.

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45 papers · 1 filter

math.CO2022★ 5 cited

Revisiting Semistrong Edge-Coloring of Graphs

Borut Lužar, Martina Mockovčiaková, Roman Soták

A matching $M$ in a graph $G$ is {\em semistrong} if every edge of $M$ has an endvertex of degree one in the subgraph induced by the vertices of $M$ . A {\em semistrong edge-colorin…

math.CO2022

The most general structure of graphs with hamiltonian or hamiltonian connected square

J. Ekstein, H. Fleischner

On the basis of recent results on hamiltonicity and hamiltonian connectedness in the square of a 2-block, we determine the most general block-cutvertex structure a graph $G$ may ha…

math.CO2021★ 8 cited

Subgraph complementation and minimum rank

Calum Buchanan, Christopher Purcell, Puck Rombach

Any finite simple graph $G = (V, E)$ can be represented by a collection $C$ of subsets of $V$ such that $uv \in E$ if and only if $u$ and $v$ appear together in an odd numb…

math.CO2020

Hamiltonian properties in generalized lexicographic products

Jan Ekstein, Jakub Teska

The lexicographic product $G [H]$ of two graphs $G$ and $H$ is obtained from $G$ by replacing each vertex with a copy of $H$ and adding all edges between any pair of copies correspo…

math.CO2020★ 4 cited

Edge-critical subgraphs of Schrijver graphs II: The general case

Tomáš Kaiser, Matěj Stehlík

We give a simple combinatorial description of an $(n - 2 k + 2)$ -chromatic edge-critical subgraph of the Schrijver graph $SG (n, k)$ , itself an induced vertex-critical subgraph o…

math.CO2020★ 1 cited

Star Edge-Coloring of Square Grids

Přemysl Holub, Borut Lužar, Erika Mihaliková +2

A star edge-coloring of a graph $G$ is a proper edge-coloring without bichromatic paths or cycles of length four. The smallest integer $k$ such that $G$ admits a star edge-coloring…

math.CO2020

Trestles in the squares of graphs

Adam Kabela, Jakub Teska

We show that the square of every connected $S (K_{1, 4})$ -free graph satisfying a matching condition has a $2$ -connected spanning subgraph of maximum degree at most~ $3$ . Furthermore,…

math.CO2019★ 10 cited

No additional tournaments are quasirandom-forcing

Robert Hancock, Adam Kabela, Daniel Kral +4

A tournament H is quasirandom-forcing if the following holds for every sequence (G_n) of tournaments of growing orders: if the density of H in G_n converges to the expected density…

math.CO2019★ 7 cited

Edge-critical subgraphs of Schrijver graphs

Tomáš Kaiser, Matěj Stehlík

For $k \geq 1$ and $n \geq 2 k$ , the Kneser graph $K G (n, k)$ has all $k$ -element subsets of an $n$ -element set as vertices; two such subsets are adjacent if they are disjoint. It was f…

math.CO2019

On forbidden induced subgraphs for K_{1,3}-free perfect graphs

Christoph Brause, Přemysl Holub, Adam Kabela +3

Considering connected $K_{1, 3}$ -free graphs with independence number at least $3$ , Chudnovsky and Seymour (2010) showed that every such graph, say $G$ , is $2 ω$ -colourable where $ω$ …

math.CO2018

On non-repetitive sequences of arithmetic progressions:the cases $k \in {4, 5, 6, 7, 8}$

Borut Lužar, Martina Mockovčiaková, Pascal Ochem +2

A $d$ -subsequence of a sequence $φ = x_{1} \dots x_{n}$ is a subsequence $x_{i} x_{i + d} x_{i + 2 d} \dots$ , for any positive integer $d$ and any $i$ , $1 \leq i \leq n$ . A \textit{ $k$ -Thue seque…

math.CO2018★ 4 cited

Complete regular dessins and skew-morphisms of cyclic groups

Yan-Quan Feng, Kan Hu, Roman Nedela +2

A dessin is a 2-cell embedding of a connected $2$ -coloured bipartite graph into an orientable closed surface. A dessin is regular if its group of orientation- and colour-preserving…

math.CO2017★ 5 cited

3-coloring triangle-free planar graphs with a precolored 9-cycle

Ilkyoo Choi, Jan Ekstein, Přemysl Holub +1

Given a triangle-free planar graph G and a 9-cycle C in G, we characterize situations where a 3-coloring of C does not extend to a proper 3-coloring of G. This extends previous res…

math.CO2017★ 9 cited

Note on list star edge-coloring of subcubic graphs

Borut Lužar, Martina Mockovčiaková, Roman Soták

{\emph A star edge-coloring} of a graph is a proper edge-coloring without bichromatic paths and cycles of length four. In this paper, we consider the list version of this coloring…

math.CO2017

Long paths and toughness of k-trees and chordal planar graphs

Adam Kabela

We show that every $k$ -tree of toughness greater than $\frac{k}{3}$ is Hamilton-connected for $k \geq 3$ . (In particular, chordal planar graphs of toughness greater than $1$ are Ha…

math.CO2017★ 1 cited

3-Flows with Large Support

Matt DeVos, Jessica McDonald, Irene Pivotto +2

We prove that every 3-edge-connected graph $G$ has a 3-flow $ϕ$ with the property that $∣ s u pp (ϕ) ∣ \geq \frac{5}{6} ∣ E (G) ∣$ . The graph $K_{4}$ demonstrates that this $\frac{5}…

math.CO2016★ 1 cited

An algebraic approach to lifts of digraphs

C. Dalfó, M. A. Fiol, M. Miller +2

We study the relationship between two key concepts in the theory of (di)graphs: the quotient digraph, and the lift $Γ^{α}$ of a base (voltage) digraph. These techniques contract or e…

math.CO2016

Decomposing planar cubic graphs

Arthur Hoffmann-Ostenhof, Tomáš Kaiser, Kenta Ozeki

The 3-Decomposition Conjecture states that every connected cubic graph can be decomposed into a spanning tree, a 2-regular subgraph and a matching. We show that this conjecture hol…

math.CO2016

Schrijver graphs and projective quadrangulations

Tomáš Kaiser, Matěj Stehlík

In a recent paper [J. Combin. Theory Ser. B}, 113 (2015), pp. 1-17], the authors have extended the concept of quadrangulation of a surface to higher dimension, and showed that ever…

math.CO2015

Jordan-like characterization of automorphism groups of planar graphs

Pavel Klavík, Roman Nedela, Peter Zeman

We investigate automorphism groups of planar graphs. The main result is a complete recursive description of all abstract groups that can be realized as automorphism groups of plana…

math.CO2015★ 3 cited

Planar graphs have two-coloring number at most 8

Zdeněk Dvořák, Adam Kabela, Tomáš Kaiser

We prove that the two-colouring number of any planar graph is at most 8. This resolves a question of Kierstead et al. [SIAM J. Discrete Math.~23 (2009), 1548--1560]. The result is…

math.CO2015★ 3 cited

First order limits of sparse graphs: Plane trees and path-width

Jakub Gajarsky, Petr Hlineny, Tomas Kaiser +5

Nesetril and Ossona de Mendez introduced the notion of first order convergence as an attempt to unify the notions of convergence for sparse and dense graphs. It is known that there…

math.CO2014★ 7 cited

Induced subgraphs with large degrees at end-vertices for hamiltonicity of claw-free graphs

Roman Čada, Binlong Li, Bo Ning +1

A graph is called \emph{claw-free} if it contains no induced subgraph isomorphic to $K_{1, 3}$ . Matthews and Sumner proved that a 2-connected claw-free graph $G$ is hamiltonian if e…

math.CO2014★ 1 cited

Solution to a problem on hamiltonicity of graphs under Ore- and Fan-type heavy subgraph conditions

Bo Ning, Shenggui Zhang, Binlong Li

A graph $G$ is called \emph{claw-o-heavy} if every induced claw ( $K_{1, 3}$ ) of $G$ has two end-vertices with degree sum at least $∣ V (G) ∣$ in $G$ . For a given graph $R$ , $G$ is call…

Revisiting Semistrong Edge-Coloring of Graphs

The most general structure of graphs with hamiltonian or hamiltonian connected square

Subgraph complementation and minimum rank

Hamiltonian properties in generalized lexicographic products

Edge-critical subgraphs of Schrijver graphs II: The general case

Star Edge-Coloring of Square Grids

Trestles in the squares of graphs

No additional tournaments are quasirandom-forcing

Edge-critical subgraphs of Schrijver graphs

On forbidden induced subgraphs for K_{1,3}-free perfect graphs

On non-repetitive sequences of arithmetic progressions:the cases k∈{4,5,6,7,8}

Complete regular dessins and skew-morphisms of cyclic groups

3-coloring triangle-free planar graphs with a precolored 9-cycle

Note on list star edge-coloring of subcubic graphs

Long paths and toughness of k-trees and chordal planar graphs

3-Flows with Large Support

An algebraic approach to lifts of digraphs

Decomposing planar cubic graphs

Schrijver graphs and projective quadrangulations

Jordan-like characterization of automorphism groups of planar graphs

Planar graphs have two-coloring number at most 8

First order limits of sparse graphs: Plane trees and path-width

Induced subgraphs with large degrees at end-vertices for hamiltonicity of claw-free graphs

Solution to a problem on hamiltonicity of graphs under Ore- and Fan-type heavy subgraph conditions

On non-repetitive sequences of arithmetic progressions:the cases $k \in {4, 5, 6, 7, 8}$