Zobrazeno 1 - 10
of 15
pro vyhledávání: '"Ruth Luo"'
Publikováno v:
Journal of Combinatorics. 12:247-268
Let $EG_r(n,k)$ denote the maximum number of edges in an $n$-vertex $r$-uniform hypergraph with no Berge cycles of length $k$ or longer. In the first part of this work, we have found exact values of $EG_r(n,k)$ and described the structure of extremal
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::a9c6e2fe391a837903e052f5972eb116
https://doi.org/10.4310/joc.2021.v12.n2.a4
https://doi.org/10.4310/joc.2021.v12.n2.a4
Publikováno v:
Journal of Combinatorial Theory, Series B. 145:450-465
We find Dirac-type sufficient conditions for a hypergraph H with few edges to be hamiltonian. We also show that these conditions guarantee that H is super-pancyclic, i.e., for each A ⊆ V ( H ) with | A | ≥ 3 , H contains a Berge cycle with vertex
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::c110197b3f73c4d3622be945958bc8ad
https://doi.org/10.1016/j.jctb.2020.06.007
https://doi.org/10.1016/j.jctb.2020.06.007
Autor:
Ruth Luo, Alexandr V. Kostochka
Publikováno v:
Discrete Applied Mathematics. 276:69-91
We show that for each k ≥ 4 and n > r ≥ k + 1 , every n -vertex hypergraph with edge sizes at least r and no Berge cycle of length at least k has at most ( k − 1 ) ( n − 1 ) r edges. The bound is exact, and we describe the extremal hypergraph
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::a8612364157a0c78a7079b9ca6739480
https://doi.org/10.1016/j.dam.2019.07.011
https://doi.org/10.1016/j.dam.2019.07.011
Autor:
Zoltán Füredi, Ruth Luo
Publikováno v:
European Journal of Combinatorics. :103692
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::c510d9b0e62898c1bf0773444b37b709
https://doi.org/10.1016/j.ejc.2023.103692
https://doi.org/10.1016/j.ejc.2023.103692
Publikováno v:
Discrete Mathematics. 342:1919-1923
A graph G is l -hamiltonian if each linear forest F with l edges contained in G can be extended to a hamiltonian cycle of G . We give a sharp upper bound for the maximum number of cliques of a fixed size in a non- l -hamiltonian graph. Furthermore, w
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::f355dedf1efd119cff010f4981391821
https://doi.org/10.1016/j.disc.2019.03.008
https://doi.org/10.1016/j.disc.2019.03.008
Autor:
Ruth Luo, Zoltán Füredi
Publikováno v:
The Electronic Journal of Combinatorics. 28
Gyárfas proved that every coloring of the edges of $K_n$ with $t+1$ colors contains a monochromatic connected component of size at least $n/t$. Later, Gyárfás and Sárközy asked for which values of $\gamma=\gamma(t)$ does the following strengthen
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::f82dbea8fa5995c819a1b1e81dbf4abc
https://doi.org/10.37236/9824
https://doi.org/10.37236/9824
Publikováno v:
The Electronic Journal of Combinatorics. 28
Let $H$ and $F$ be hypergraphs. We say $H$ {\em contains $F$ as a trace} if there exists some set $S \subseteq V(H)$ such that $H|_S:=\{E\cap S: E \in E(H)\}$ contains a subhypergraph isomorphic to $F$. In this paper we give an upper bound on the num
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::485cfdda910a1409505476b5517fcd50
https://doi.org/10.37236/9760
https://doi.org/10.37236/9760
Publikováno v:
The Electronic Journal of Combinatorics. 27
We consider two extremal problems for set systems without long Berge cycles. First we give Dirac-type minimum degree conditions that force long Berge cycles. Next we give an upper bound for the number of hyperedges in a hypergraph with bounded circum
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::c5f540dc1c72d950b9e5024c0a20a041
https://doi.org/10.37236/9346
https://doi.org/10.37236/9346
A hypergraph $\mathcal H$ is super-pancyclic if for each $A \subseteq V(\mathcal H)$ with $|A| \geq 3$, $\mathcal H$ contains a Berge cycle with base vertex set $A$. We present two natural necessary conditions for a hypergraph to be super-pancyclic,
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::7c0a3c389e7b88beb979b5b0d5850e78
Publikováno v:
Discrete Mathematics. 341:1253-1263
The Erdős–Gallai Theorem states that for k ≥ 3 , any n -vertex graph with no cycle of length at least k has at most 1 2 ( k − 1 ) ( n − 1 ) edges. A stronger version of the Erdős–Gallai Theorem was given by Kopylov: If G is a 2-connected
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::045cfdb66c06e1c2950a31cc326c838b
https://doi.org/10.1016/j.disc.2017.12.018
https://doi.org/10.1016/j.disc.2017.12.018