In this paper we introduce games with optimistic aspirations and identify attractive allocation rules for such games through axiomatizations. A game with optimistic aspirations specifies two values for each coalition of players: the first value is the worth that the players in the coalition can...

Total clan games are characterized using monotonicity, veto power of the clan members, and a concavity condition reflecting the decreasing marginal contribution of non-clan members to growing coalitions. This decreasing marginal contribution is incorporated in the notion of a bi-monotonic...