Abstract
Letk t(G) be the number of cliques of ordert in the graphG. For a graphG withn vertices let\(c_t (G) = \frac{{k_t (G) + k_t (\bar G)}}{{\left( {\begin{array}{*{20}c} n \\ t \\ \end{array} } \right)}}\). Letc t(n)=Min{c t(G)∶∇G∇=n} and let\(c_t = \mathop {\lim }\limits_{n \to \infty } c_t (n)\). An old conjecture of Erdös [2], related to Ramsey's theorem states thatc t=21-(t/2). Recently it was shown to be false by A. Thomason [12]. It is known thatc t(G)≈21-(t/2) wheneverG is a pseudorandom graph. Pseudorandom graphs — the graphs “which behave like random graphs” — were inroduced and studied in [1] and [13]. The aim of this paper is to show that fort=4,c t(G)≥21-(t/2) ifG is a graph arising from pseudorandom by a small perturbation.
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Research supported by NSERC grant OGP0025112
Research supported by NSF grant DMS 9011850
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Franek, F., Rödl, V. Ramsey problem on multiplicities of complete subgraphs in nearly quasirandom graphs. Graphs and Combinatorics 8, 299–308 (1992). https://doi.org/10.1007/BF02351585
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DOI: https://doi.org/10.1007/BF02351585