Upper bounds for Turan numbers

摘要

A system of r-element subsets (blocks) of an n-element set X(n) is called a Turan (n, k, r)-system if every k-element subset of X(n) contains at least one of the blocks. The Turan number T(n, k, r) is the minimum size of such a system. We prove upper estimates [GRAPHICS] (C) 1997 Academic Press