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Weakly union-free twofold triple systems

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Abstract

In this paper, we settle a problem of Frankl and Füredi, which is a special case of a problem of Erdös, determining the maximum number of hyperedges in a 3-uniform hypergraph in which no two pairs of distinct hyperedges have the same union. The extremal case corresponds to the existence of weakly union-free twofold triple systems, which is settled here with six definite and four possible exceptions. An application to group testing is also given.

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In memory of Paul Erdös

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Chee, Y.M., Colbourn, C.J. & Ling, A.C.H. Weakly union-free twofold triple systems. Annals of Combinatorics 1, 215–225 (1997). https://doi.org/10.1007/BF02558476

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