Abstract

duesseldorf.de We propose a new representation setting for hedonic games, where each agent partitions the set of other agents into friends, enemies, and neutral agents, with friends and enemies being ranked. Under the assumption that preferences are monotonic (respectively, anti-monotonic) with respect to the addition of friends (respectively, en-emies), we propose a bipolar extension of the Bossong–Schweigert extension principle, and use this principle to derive the (partial) preferences of agents over coalitions. Then, for a number of solu-tion concepts, we characterize partitions that necessarily (respec-tively, possibly) satisfy them, and identify the computational com-plexity of the associated decision problems. Alternatively, we sug-gest cardinal comparability functions in order to extend to com-plete preference orders consistent with the generalized Bossong– Schweigert order.