Modeling interaction among artificial agents is a challenging task. Argumentation, auction, dialogue games and agent communication languages are proposed as mechanisms to model agent interaction. Among different mechanisms to model interaction among agents, dialogue game protocols is most significant. In this thesis I model a dialogue game in defeasible logic. I have two research goals. First, previous development of dialogue game protocols does not consider the strategic behaviour of agents. In this thesis I model the strategic behaviour of agents. Second, as more and more dialogue game protocols are developed there is a need to compare these protocols so that an appropriate protocol can be chosen for a given problem. Previous attempts to compare dialogue game protocols are based on functional comparison of components of a protocol. In this thesis I develop a new semantics for locution. Based on this semantics, dialogue game protocols can be compared so the protocol that can convey the right meaning can be identfied.