 Swap robustness for disjoint winning coalitions

A zero-one coalitional game has this property if exchanging one player each way between two disjoint winning coalitions leaves at least one winning. Any weighted voting game satisfies it: the exchange preserves their aggregate weight, which is at least twice the quota, whereas two losing coalitions would have aggregate weight strictly below twice the quota.

The disjointness restriction is substantive. If every winning coalition contains a common player, the condition is vacuous. It is consequently weaker than restrictions allowing exchanges between overlapping winning coalitions, and does not characterize weighted voting games.