منابع مشابه
Non-uniform Turán-type problems
Given positive integers n, k, t, with 2 ≤ k ≤ n, and t < 2, let m(n, k, t) be the minimum size of a family F of (nonempty distinct) subsets of [n] such that every k-subset of [n] contains at least t members of F , and every (k − 1)-subset of [n] contains at most t− 1 members of F . For fixed k and t, we determine the order of magnitude of m(n, k, t). We also consider related Turán numbers T≥r(n...
متن کاملTurán Problems on Non-Uniform Hypergraphs
A non-uniform hypergraph H = (V,E) consists of a vertex set V and an edge set E ⊆ 2V ; the edges in E are not required to all have the same cardinality. The set of all cardinalities of edges in H is denoted by R(H), the set of edge types. For a fixed hypergraph H, the Turán density π(H) is defined to be limn→∞maxGn hn(Gn), where the maximum is taken over all H-free hypergraphs Gn on n vertices ...
متن کاملExact solution of some Turán-type problems
Fifteen years ago Chvatal conjectured that if 9 is a family of k subsets of an nset, 191 > (;I;), d is an arbitrary integer with d< k 1 and (d+ 1) k n,(k). in a more general framework. Another problem which is solved asymp...
متن کاملMore results on Ramsey - Turán Type problems
In her paper [9] the third author raised a general scheme of new problems. These problems can be considered as common generalizations of the problems treated in the classical results of Ramsey and Turan Since 1969 she and the first author have published a sequence of papers on the subjcc’i [5], [(;I. [4]. This work is a continuation of the above sequence. We are going to define the Ramsey-Turin...
متن کاملRainbow Turán Problems
For a fixed graph H, we define the rainbow Turán number ex∗(n,H) to be the maximum number of edges in a graph on n vertices that has a proper edge-colouring with no rainbow H. Recall that the (ordinary) Turán number ex(n,H) is the maximum number of edges in a graph on n vertices that does not contain a copy of H. For any non-bipartite H we show that ex∗(n,H) = (1+o(1))ex(n,H), and if H is colou...
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ژورنال
عنوان ژورنال: Journal of Combinatorial Theory, Series A
سال: 2005
ISSN: 0097-3165
DOI: 10.1016/j.jcta.2004.11.010