- INSTANCE: Graph , monotone activation functions for the edges , bifamily of subsets of
- SOLUTION: assignment such that the set of activated edges (i.e. ) covers
- COST FUNCTION:
- OBJECTIVE: Minimize
*Approx.:*Admits an -approximation algorithm for the case when is an uncrossable family, where is the set of all subsets for which and does not contain two distinct inclusion-minimal members of the family [92]*Comment:*A bifamily of subsets of is a set of pairs of subsets of such that for each , and the following property holds: For all and in , implies and implies . A set of edges covers if for each in , there is an edge which goes from to .