... least k − non-isomorphic constructions that attain the bound if n = 3k Kostochka [5] generalized Brown’s constructions to give 2k−2 nonisomorphic constructions if n = 3k These constructions are easiest ... If abu forming an edge does not depend on u, then either abu and abv both form an edge or else neither We can thus restrict our attention to the DC and DD lines The only way for abu to form an ... pp 187– a 197, J´nos Bolyai Math Soc., Budapest, 1994 a [5] A Kostochka, A class of constructions for Tur´n’s (3, 4) problem Combinatorica a (1982), 187-192 [6] T Spencer, On the size of independent...