This article continues the investigation started in [19] on the role of possibilistic mixed strategies in strategic-form games. In this earlier work we assumed, as standard in possibility theory, that joint possibility distributions were computed by combining possibilistic mixed strategies with the minimum t-norm. In this paper, we investigate the consequences of defining joint possibility distributions by using any continuous t-norm, with players' expected utilities based on the Choquet integral. We characterise under which conditions a pair of possibilistic mixed strategies is an equilibrium, generalising the results first presented in [19], and also show that the set of equilibria in possibilistic mixed strategies depends on the set of idempotent elements of a t-norm and not just on the chosen t-norm.

Rational verification is concerned with establishing whether a given temporal logic formula φ is satisfied in some or all equilibrium computations of a multi-agent system – that is, whether the system will exhibit the behaviour φ under the assumption that agents within the system act rationally in pursuit of their preferences. After motivating and introducing the framework of rational verification, we present formal models through which rational verification can be studied, and survey the complexity of key decision problems. We give an overview of a prototype software tool for rational verification, and conclude with a discussion and related work.

Boolean games provide a simple, compact, and theoretically attractive abstract model for studying multiagent interactions in settings where players will act strategically in an attempt to achieve individual goals. A standard critique of Boolean games, however, is that the strictly dichotomous nature of the preference relations induced by Boolean goals inevitably trivialises the nature of such strategic interactions: a player is assumed to be indifferent between all outcomes that satisfy her goal, and indifferent between all outcomes that do not satisfy her goal. While various proposals have been made to overcome this limitation, many of these proposals require the inclusion of nonlogical structures into games to capture nondichotomous preferences. In this article, we introduce Łukasiewicz games, which overcome this limitation by allowing goals to be specified using Łukasiewicz logics . By expressing goals as formulae of Łukasiewicz logics, we can express a much richer class of utility functions for players than is possible using classical Boolean logic: we can express every continuous piecewise linear polynomial function with rational coefficients over [0, 1] n as well as their finite-valued restrictions over {0, 1/ k , …, ( k − 1)/ k , 1} n . We thus obtain a representation of nondichotomous preference structures within a purely logical framework. After introducing the formal framework of Łukasiewicz games, we present a number of detailed worked examples to illustrate the framework, and then investigate some of their theoretical properties. In particular, we present a logical characterisation of the existence of Nash equilibria in finite and infinite Łukasiewicz games. We conclude by briefly discussing issues of computational complexity.

Possibility and necessity measures are commonly defined over Boolean algebras. This work considers a generalization of these kinds of measures over MV-algebras as a possibilistic counterpart of the (probabilistic) notion of state on MV-algebras. Two classes of possibilistic states over MV-algebras of functions are characterized in terms of (generalized) Sugeno integrals. For reasoning about these representable classes of possibilistic states, we introduce many-valued modal logics based on the Rational Łukasiewicz Logic, that are shown to be complete with respect to corresponding classes of Kripke models equipped with those states.

We propose a method for characterizing the complexity of satisfiability and tautologicity of equational theories of varieties of algebras by relying on their representability in the theory of the ordered additive group of reals R with rational constants. We call semilinear those varieties which are generated by a subclass of algebras in which the operations are representable as semilinear functions with rational coefficients. Those functions are definable in the theory of R which admits quantifier elimination and whose existential theory is NP-complete. We prove that there is a polynomial time translation of the equational theories of semilinear varieties into the existential theory of R. Then, if the variety is generated (up to isomorphism) by one semilinear algebra, the satisfiability problem is in NP, while the tautologicity problem is in co-NP. We apply this method in order to provide a comprehensive study of complexity of several varieties related to logics based on left-continuous conjunctive uninorms and left-continuous t-norms.

In this work we investigate several complexity and definability problems for the logic ŁΠ12⁠. We show that the universal fragment of the theory of real closed fields can be faithfully interpreted in such a logic. Then we investigate the logics of t-norms definable in ŁΠ12⁠, and we prove that they are all in PSPACE. Finally we show that the most important fuzzy logics are complete with respect to classes of t-norms which are definable in ŁΠ12⁠.