タイトル：A characterization of weak Maskin monotonicity in an allocation problem with indivisible goods
We consider an allocation problem with indivisible goods, and characterize weak Maskin monotonic allocation rules based on the
robustness to group manipulation. Specifically, we introduce a new condition called unimprovement property of unmatched agents which means that
unmatched agents cannot be strictly better off through any group manipulation.
We show that a non-wasteful allocation rule satisfies weak Maskin monotonicity if and only if it satisfies unimprovement property of unmatched agents and weak group strategy-proofness.