Zobrazeno 1 - 10
of 989
pro vyhledávání: '"Wolf, P. h."'
Autor:
Goedgebeur, Jan, Mattiolo, Davide, Mazzuoccolo, Giuseppe, Renders, Jarne, Toffanetti, Luca, Wolf, Isaak H.
A recent result by Kardo\v{s}, M\'a\v{c}ajov\'a and Zerafa [J. Comb. Theory, Ser. B. 160 (2023) 1--14] related to the famous Berge-Fulkerson conjecture implies that given an arbitrary set of odd pairwise edge-disjoint cycles, say $\mathcal O$, in a b
Externí odkaz:
http://arxiv.org/abs/2411.09806
An $r$-regular graph is an $r$-graph, if every odd set of vertices is connected to its complement by at least $r$ edges. Seymour [On multicolourings of cubic graphs, and conjectures of Fulkerson and Tutte.~\emph{Proc.~London Math.~Soc.}~(3), 38(3): 4
Externí odkaz:
http://arxiv.org/abs/2411.01753
Petersen's seminal work in 1891 asserts that the edge-set of a cubic graph can be covered by distinct perfect matchings if and only if it is bridgeless. Actually, it is known that for a very large fraction of bridgeless cubic graphs, every edge belon
Externí odkaz:
http://arxiv.org/abs/2402.08538
Autor:
Wolf, Isaak H.
Publikováno v:
J. Graph Theory (2024), 1-14
Let $G$ be a simple graph and let $n,m$ be two integers with $0
Externí odkaz:
http://arxiv.org/abs/2312.11095
An $r$-regular graph is an $r$-graph, if every odd set of vertices is connected to its complement by at least $r$ edges. Let $G$ and $H$ be $r$-graphs. An $H$-coloring of $G$ is a mapping $f\colon E(G) \to E(H)$ such that each $r$ adjacent edges of $
Externí odkaz:
http://arxiv.org/abs/2305.08619
Autor:
Steffen, Eckhard, Wolf, Isaak H.
Publikováno v:
Discrete Mathematics (2023)
We study rotation $r$-graphs and show that for every $r$-graph $G$ of odd regularity there is a simple rotation $r$-graph $G'$ such that $G$ can be obtained form $G'$ by a finite number of $2$-cut reductions. As a consequence, some hard conjectures a
Externí odkaz:
http://arxiv.org/abs/2304.12710
For $0 \leq t \leq r$ let $m(t,r)$ be the maximum number $s$ such that every $t$-edge-connected $r$-graph has $s$ pairwise disjoint perfect matchings. There are only a few values of $m(t,r)$ known, for instance $m(3,3)=m(4,r)=1$, and $m(t,r) \leq r-2
Externí odkaz:
http://arxiv.org/abs/2208.14835
Autor:
Steffen, Eckhard, Wolf, Isaak H.
Publikováno v:
Discrete Applied Mathematics, 337:185-189, 2023
The paper studies edge-coloring of signed multigraphs and extends classical Theorems of Shannon and K\"onig to signed multigraphs. We prove that the chromatic index of a signed multigraph $(G,\sigma_G)$ is at most $\lfloor \frac{3}{2} \Delta(G) \rflo
Externí odkaz:
http://arxiv.org/abs/2206.11052
Publikováno v:
SIAM J. Discrete Math., 37 (2023), 1548-1565
Thomassen [Problem 1 in Factorizing regular graphs, J. Combin. Theory Ser. B, 141 (2020), 343-351] asked whether every $r$-edge-connected $r$-regular graph of even order has $r-2$ pairwise disjoint perfect matchings. We show that this is not the case
Externí odkaz:
http://arxiv.org/abs/2206.10975
Autor:
Steffen, Eckhard, Wolf, Isaak H.
Publikováno v:
Graphs and Combinatorics 38, 104 (2022)
A finite simple connected graph $G$ with maximum degree $k$ is $k$-critical if it has chromatic index $\chi'(G)=k+1$ and $\chi'(G-e)=k$ for every edge $e\in E(G)$. Bej and the first author raised the question whether every $k$-critical graph has an e
Externí odkaz:
http://arxiv.org/abs/2109.11447