\input zb-basic \input zb-ioport \iteman{io-port 05242146} \itemau{Ragone, Azzurra; Straccia, Umberto; Di Noia, Tommaso; Di Sciascio, Eugenio; Donini, Francesco M.} \itemti{Towards a fuzzy logic for automated multi-issue negotiation.} \itemso{Hartmann, Sven (ed.) et al., Foundations of information and knowledge systems. 5th international symposium, FoIKS 2008, Pisa, Italy, February 11--15, 2008. Proceedings. Berlin: Springer (ISBN 978-3-540-77683-3/pbk). Lecture Notes in Computer Science 4932, 381-396 (2008).} \itemab Summary: We present a novel logic-based approach to automate multi-issue bilateral negotiation in e-marketplaces. In such frameworks issues to negotiate on can be multiple, interrelated, and may not be fixed in advance. We use logic to model relations among issues and to allow agents express their preferences on them. In particular, we introduce the logic $\mathcal{P(N)}$, a fuzzy propositional logic extended with concrete domains in order to handle numerical, as well as non numerical features, and to deal with vagueness in buyer/seller preferences. Hence, agents can express preferences as e.g., I am searching for a passenger car costing about 25000EUR yet if the car has a GPS system and more than two-year warranty I can spend up to 28000EUR. We illustrate the theoretical framework, the logical language, the protocol we adopt and show that using a mediator with a proactive behavior we can compute Pareto-efficient agreements. \itemrv{~} \itemcc{} \itemut{} \itemli{doi:10.1007/978-3-540-77684-0\_25} \end