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Published online by Cambridge University Press: 20 November 2018
In this note we consider some problems related to the following question:What is the smallest integer m(n) for which there exists a family Fn of sets A1, A2,…, Am(n)with the following properties, (i) each member of Fn has nelements and (ii) if S is a set which meets each member of Fn,then S contains at least one member of Fn?
Erdős and Hajnal [1] observed that
and that m(l) = 1, m(2) = 3, m(3) = 7.