In this paper we present a cut-free sequent calculus, called SeqS, for some standard conditional logics. The calculus uses labels and transition formulas and can be used to prove decidability and space complexity bounds for the respective logics. We also show that these calculi can be the base for uniform proof systems. Moreover, we present CondLean, a theorem prover in Prolog for these calculi. ACM Reference Format:Olivetti, N., Pozzato, G., and Schwind, C., 2007. A sequent calculus and a theorem prover for standard conditional logics. ACM Trans. Comput.Article 22 / 2 • N. Olivetti et al.

In this paper we develop a logical framework for specifying and verifying systems of communicating agents and interaction protocols. The framework is based on Dynamic Linear Time Temporal Logic (DLTL), which extends LTL by strengthening the until operator by indexing it with the regular programs of dynamic logic. The framework provides a simple formalization of the communicative actions in terms of their effects and preconditions and the specification of an interaction protocol by means of temporal constraints. We adopt a social approach to agent communication, where communication can be described in terms of changes in the social relations between participants, and protocols in terms of creation, manipulation and satisfaction of commitments among agents. The description of the interaction protocol and of communicative actions is given in a temporal action theory, and agent programs, when known, can be specified as complex actions (regular programs in DLTL). The paper addresses several kinds of verification problems (including the problem of verifying compliance of agents with the protocol), which can be formalized either as validity or as satisfiability problems in the temporal logic and can be solved by model checking techniques. In particular, we show that the verification of the compliance of an agent with the protocol requires to move to the logic DLTL ⊗ , the product version of DLTL.

Abstract. In this paper we address the problem of specifying and verifying systems of communicating agents in a Dynamic Linear Time Temporal Logic (DLTL). This logic provides a simple formalization of the communicative actions in terms of their effects and preconditions. Furthermore it allows to specify interaction protocols by means of temporal constraints representing permissions and commitments. Agent programs, when known, can be formulated in DLTL as complex actions (regular programs). The paper addresses several kinds of verification problems including the problem of compliance of agents to the protocol, and describes how they can be solved by model checking in DLTL using automata.

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We present a tableau calculus for some fundamental systems of propositional conditional logics. We consider the conditional logics that can be characterized by preferential semantics (i.e., possible world structures equipped with a family of preference relations). For these logics, we provide a uniform completeness proof of the axiomatization with respect to the semantics, and a uniform labeled tableau procedure.