منابع مشابه
Supersaturation For Ramsey-Turán Problems
For an l-graph G, the Turán number ex(n,G) is the maximum number of edges in an n-vertex l-graph H containing no copy of G. The limit π(G) = limn→∞ ex (n,G)/ ( n l ) is known to exist [8]. The Ramsey-Turán density ρ(G) is defined similarly to π(G) except that we restrict to only those H with independence number o(n). A result of Erdős and Sós [3] states that π(G) = ρ(G) as long as for every edg...
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 کاملA new class of Ramsey-Turán problems
We introduce and study a new type of Ramsey-Turán problems, a typical example of which is the following one: Let " > 0 and G be a graph of su¢ ciently large order n with minimum degree (G) > 3n=4: If the edges of G are colored in blue or red, then for all k 2 [4; b(1=8 ")nc] ; there exists a monochromatic cycle of length k: Keywords: Ramsey-Turán problems; minimum degree; monochromatic cycles. ...
متن کاملExplicit constructions of triple systems for Ramsey-Turán problems
We explicitly construct four infinite families of irreducible triple systems with Ramsey-Turán density less than the Turán density. Two of our families generalize isolated examples of Sidorenko [14], and the first author and Rödl [12]. Our constructions also yield two infinite families of irreducible triple systems whose Ramsey-Turán densities are exactly determined. For an r-graph F , the Turá...
متن کاملRamsey and Turán-type problems in bipartite geometric graphs
A = {(1, 0), (2, 0), . . . , (n, 0)}, B = {((1, 1), (2, 1), . . . , (n, 1)} and the edge ab is the line segment joining a ∈ A and b ∈ B in R. This model is essentially the same as the cyclic bipartite graphs and ordered bipartite graphs considered earlier by several authors. Subgraphs — paths, trees, double stars, matchings — are called non-crossing if they do not contain edges with common inte...
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ژورنال
عنوان ژورنال: Combinatorica
سال: 2006
ISSN: 0209-9683,1439-6912
DOI: 10.1007/s00493-006-0018-x