Enhancing Commitment Machines

Agent interaction protocols are usually specified in terms of permissi- ble sequences of messages. This representation is, unfortunately, brittle and does not allow for flexibility and robustness. The commitment machinesframework of Yolum and Singh aims to provide more flexibility and robustness by defining interactions in terms of the commitments of agents. In this paper we identify a number of areas where the commitment machines framework needs improvement and propose an improved version. In particular we improve the way in which commitments are discharged and the way in which pre-conditions are specified.