An antichain on a set is a T_0-antichain if for every two distinct points of the set there exists a member of the antichain containing one but not the other point. T_1-hypergraph is a hypergraph which for every ordered pair (u,v) of distinct nodes has a hyperedge containing u but not v.
REFERENCES
V. Jovovic, G. Kilibarda, On enumeration of the class of all monotone Boolean functions, in preparation.