Zobrazeno 1 - 10
of 341
pro vyhledávání: '"Sales, Marcelo"'
The $k$-representation number of a graph $G$ is the minimum cardinality of the system of vertex subsets with the property that every edge of $G$ is covered at least $k$ times while every non-edge is covered at most $(k-1)$ times. In particular, for $
Externí odkaz:
http://arxiv.org/abs/2403.01563
Autor:
Rödl, Vojtěch, Sales, Marcelo
A set of points $S$ in Euclidean space $\mathbb{R}^d$ is called \textit{Ramsey} if any finite partition of $\mathbb{R}^{\infty}$ yields a monochromatic copy of $S$. While characterization of Ramsey set remains a major open problem in the area, a stro
Externí odkaz:
http://arxiv.org/abs/2402.17137
In their classical paper, Erd\H{o}s, Goodman and Posa studied the representation of a graph by vertex set $[n]$ with a family of subsets $S_1,\dots, S_n$ with the property that $\{i,j\}$ is an edge iff $S_i\cap S_j\neq \emptyset$. In this note, we co
Externí odkaz:
http://arxiv.org/abs/2402.16984
We construct for every integer $k\geq 3$ and every real $\mu\in(0, \frac{k-1}{k})$ a set of integers $X=X(k, \mu)$ which, when coloured with finitely many colours, contains a monochromatic $k$-term arithmetic progression, whilst every finite $Y\subse
Externí odkaz:
http://arxiv.org/abs/2311.08556
Given $\alpha>0$ and an integer $\ell\geq5$, we prove that every sufficiently large $3$-uniform hypergraph $H$ on $n$ vertices in which every two vertices are contained in at least $\alpha n$ edges contains a copy of $C_\ell^{-}$, a tight cycle on $\
Externí odkaz:
http://arxiv.org/abs/2211.12721
Autor:
Sales, Marcelo
A $(k+r)$-uniform hypergraph $H$ on $(k+m)$ vertices is an $(r,m,k)$-daisy if there exists a partition of the vertices $V(H)=K\cup M$ with $|K|=k$, $|M|=m$ such that the set of edges of $H$ is all the $(k+r)$-tuples $K\cup P$, where $P$ is an $r$-tup
Externí odkaz:
http://arxiv.org/abs/2211.10385
Daisies are a special type of hypergraphs introduced by Bollob\'{a}s, Leader and Malvenuto. An $r$-daisy determined by a pair of disjoint sets $K$ and $M$ is the $(r+|K|)$-uniform hypergraph $\{K\cup P:\: P\in M^{(r)}\}$. In [Combin. Probab. Comput.
Externí odkaz:
http://arxiv.org/abs/2211.10377
Autor:
Sales, Marcelo, Schülke, Bjarne
Katona's intersection theorem states that every intersecting family $\mathcal F\subseteq[n]^{(k)}$ satisfies $\vert\partial\mathcal F\vert\geq\vert\mathcal F\vert$, where $\partial\mathcal F=\{F\setminus x:x\in F\in\mathcal F\}$ is the shadow of $\ma
Externí odkaz:
http://arxiv.org/abs/2206.04278
Autor:
Rödl, Vojtech, Sales, Marcelo
For a $k$-uniform hypergraph $F$ we consider the parameter $\Theta(F)$, the minimum size of a clique cover of the of $F$. We derive bounds on $\Theta(F)$ for $F$ belonging to various classes of hypergraphs.
Comment: 14 pages
Comment: 14 pages
Externí odkaz:
http://arxiv.org/abs/2206.01844
A well-known result of Ajtai et al. from 1982 states that every $k$-graph $H$ on $n$ vertices, with girth at least five, and average degree $t^{k-1}$ contains an independent set of size $c n (\log t)^{1/(k-1)}/t$ for some $c>0$. In this paper we show
Externí odkaz:
http://arxiv.org/abs/2205.02877