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Turán problems for vertex-disjoint cliques in multi-partite hypergraphs
Discrete Mathematics ( IF 0.8 ) Pub Date : 2020-10-01 , DOI: 10.1016/j.disc.2020.112005
Erica L.L. Liu , Jian Wang

Let s, r, k, n1, . . . , nr be integers satisfying 2 ≤ s ≤ r and n1 ≤ n2 ≤ · · · ≤ nr. For two s-uniform hypergraphs H and F , the Turán number exs(H,F ) is the maximum number of edges in an F -free subgraph of H . De Silva, Heysse, and Young determined ex2(Kn1,...,nr , kK2) and De Silva, Heysse, Kapilow, Schenfisch and Young determined ex2(Kn1,...,nr , kKr). In this paper, we consider three Turán type problems for k disjoint cliques in r-partite s-graphs. First, we consider a multi-partite version of Erdős matching conjecture and determine exs(K (s) n1,...,nr , kK (s) s ) for n1 ≥ sk + sr. Using a probabilistic argument, we determine exs(K (s) n1,...,nr , kK (s) r ) for all n1 ≥ k. Recently, Alon and Shikhelman determined the generalized Turán number ex(Kn,Ks, F ) asymptotically for any F , which is the maximum number of copies of Ks in an F free graph on n vertices. Utilizing Bollobás’s Two Families Theorem, we determine ex(Kn1,...,nr ,Ks, kKr) when n3 is sufficiently larger than k.

中文翻译:

多部分超图中顶点不相交团的图兰问题

让 s, r, k, n1, . . . , nr 是满足 2 ≤ s ≤ r 和 n1 ≤ n2 ≤ · · · ≤ nr 的整数。对于两个 s-uniform 超图 H 和 F ,图兰数 exs(H,F ) 是 H 的无 F 子图中的最大边数。De Silva、Heysse 和 Young 确定了 ex2(Kn1,...,nr , kK2),De Silva、Heysse、Kapilow、Schenfisch 和 Young 确定了 ex2(Kn1,...,nr , kKr)。在本文中,我们考虑 r 部分 s 图中 k 个不相交团的三个图兰类型问题。首先,我们考虑 Erdős 匹配猜想的多部分版本,并确定 exs(K (s) n1,...,nr , kK (s) s ) for n1 ≥ sk + sr。使用概率论点,我们为所有 n1 ≥ k 确定 exs(K (s) n1,...,nr , kK (s) r )。最近,Alon 和 Shikhelman 渐近地确定了任何 F 的广义图兰数 ex(Kn,Ks, F ),这是在 n 个顶点上的 F 自由图中 Ks 的最大副本数。利用 Bollobás 的两个家庭定理,当 n3 足够大于 k 时,我们确定 ex(Kn1,...,nr ,Ks, kKr)。
更新日期:2020-10-01
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