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Giardini F.,CNR Institute of Neuroscience | Paolucci M.,CNR Institute of Neuroscience | Villatoro D.,IIIA | Conte R.,CNR Institute of Neuroscience
Advances in Intelligent Systems and Computing

In an environment in which free-riders are better off than cooperators, social control is required to foster and maintain cooperation. There are two main paths through which social control can be applied: punishment and reputation. Our experiments explore the efficacy of punishment and reputation on cooperation rates, both in isolation and in combination. Using a Public Goods Game, we are interested in assessing how cooperation rates change when agents can play one of two different reactive strategies, i.e., they can pay a cost in order to reduce the payoff of free-riders, or they can know others' reputation and then either play defect with free-riders, or refuse to interact with them. Cooperation is maintained at a high level through punishment, but also reputation-based partner selection proves effective in maintaining cooperation. However, when agents are informed about free-riders' reputation and play Defect, cooperation decreases. Finally, a combination of punishment and reputation-based partner selection leads to higher cooperation rates. © Springer-Verlag Berlin Heidelberg 2014. Source

Ansotegui C.,DIEI | Bonet M.L.,Polytechnic University of Catalonia | Levy J.,IIIA
Proceedings of the National Conference on Artificial Intelligence

We present and implement a Weighted Partial MaxSAT solver based on successive calls to a SAT solver. We prove the correctness of our algorithm and compare our solver with other Weighted Partial MaxSAT solvers. Copyright © 2010, Association for the Advancement of Artificial Intelligence (www.aaai.org). All rights reserved. Source

Cerami M.,IIIA | Straccia U.,CNR Institute of Neuroscience
Information Sciences

Recently there have been some unexpected results concerning Fuzzy Description Logics (FDLs) with General Concept Inclusions (GCIs). They show that, unlike the classical case, the DL ALC with GCIs does not have the finite model property under Łukasiewicz Logic or Product Logic, the proposed reasoning algorithms are neither correct nor complete and, specifically, knowledge base satisfiability is an undecidable problem for Product Logic. In this work, we show that knowledge base satisfiability is also an undecidable problem for Łukasiewicz Logic. We additionally provide a decision algorithm for acyclic ALC knowledge bases under Łukasiewicz Logic via a Mixed Integer Linear Programming (MILP) based procedure (note, however, that the decidability of this problem is already known). While similar MILP based algorithms have been proposed in the literature for acyclic ALC knowledge bases under Łukasiewicz Logic, none of them exhibit formal proofs of their correctness and completeness, which is the additional contribution here. © 2012 Elsevier Inc. All rights reserved. Source

Ansotegui C.,University of Lleida | Bofill M.,University of Girona | Manya F.,IIIA | Villaret M.,University of Girona
Proceedings of The International Symposium on Multiple-Valued Logic

There is a relatively large number of papers dealing with complexity and proof theory issues of infinitely-valued logics. Nevertheless, little attention has been paid so far to the development of efficient solvers for such logics. In this paper we show how the technology of Satisfiability Modulo Theories (SMT) can be used to build efficient automated theorem provers for relevant infinitely-valued logics, including Łukasiewicz, Gödel and Product logics. Moreover, we define a test suite for those logics, and report on an experimental investigation that evaluates the practical complexity of Łukasiewicz and Gödel logics, and provides empirical evidence of the good performance of SMT technology for automated theorem proving on infinitely-valued logics. © 2012 IEEE. Source

Ansotegui C.,University of Lleida | Bofill M.,University of Girona | Manya F.,IIIA | Villaret M.,University of Girona
Proceedings - 41st IEEE International Symposium on Multiple-Valued Logic, ISMVL 2011

We extend the language of signed many-valued clausal forms with linear integer arithmetic constraints. In this way, we get a simple modeling language in which a wide range of practical combinatorial problems admit compact and natural encodings. We then define efficient translations from our language into the SAT and SMT formalism, and propose to use SAT and SMT solvers for finding solutions. © 2011 IEEE. Source

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