Maximum Hitting for n Sufficiently Large

Abstract

For a left-compressed intersecting family A ⊆[n](r) and a set X ⊆ [n], let (Formula Presented). Borg asked: for which X is {pipe}A(X){pipe} maximised by taking A to be all r-sets containing the element 1? We determine exactly which X have this property, for n sufficiently large depending on r. © 2013 Springer Japan.