@InProceedings{yokoo05a,
  author =	 {Makoto Yokoo and Vincent Conitzer and Tuomas
                  Sandholm and Naoki Ohta and Atshushi Iwasaki},
  title =	 {Coalition Games in Open Anonymous Environments},
  booktitle =	 {Proceedings of the Twentieth National Conference on
                  Artificial Intelligence},
  crossref = 	 {aaai05},
  pages =	 {509--514},
  year =	 2005,
  address =	 {Menlog Park, California},
  publisher =	 {{AAAI Press}},
  abstract =	 {Coalition formation is a key aspect of automated
                  negotiation among self-interested agents. In order
                  for coalitions to be stable, a key question that
                  must be answered is how the gains from cooperation
                  are to be distributed. Various solution concepts
                  (such as the Shapley value, core, least core, and
                  nucleolus) have been proposed. In this paper, we
                  demonstrate how these concepts are vulnerable to
                  various kinds of manipulations in open anonymous
                  environments such as the Internet. These
                  manipulations include submitting false names (one
                  acting as many), collusion (many acting as one), and
                  the hiding of skills. To address these threats, we
                  introduce a new solution concept called the
                  anonymity-proof core, which is robust to these
                  manipulations. We show that the anonymity-proof core
                  is characterized by certain simple axiomatic
                  conditions. Furthermore, we show that by relaxing
                  these conditions, we obtain a concept called the
                  least anonymity-proof core, which is guaranteed to
                  be non-empty. We also show that computational
                  hardness of manipulation may provide an alternative
                  barrier to manipulation.},
  keywords =     {multiagent coalitions security},
  url = 	 {http://jmvidal.cse.sc.edu/library/yokoo05a.pdf}
}