Modal context restriction for multiagent BDI logics

We present and discuss a novel language restriction for modal logics for multiagent systems, called modal context restriction, that reduces the complexity of the satisfiability problem from EXPTIME complete to NPTIME complete. We focus on BDI multimodal logics that contain fix-point modalities like common beliefs and mutual intentions together with realism and introspection axioms. We show how this combination of modalities and axioms affects complexity of the satisfiability problem and how it can be reduced by restricting the modal context of formulas.

Tutorial on Reasoning in Expressive Non-Classical Logics with Isabelle/HOL

Non-classical logics (such as modal logics, description logics, conditional logics, multi-valued logics, hybrid logics, etc.) have many applications in artificial intelligence. In this tutorial, we will demonstrate a generic approach to automate propositional and quantified variants of non-classical logics using theorem proving systems for classical higher-order logic. Our particular focus will be on quantified multimodal logics. We will present and discuss a semantical embedding of quantified multimodal logics into classical higher-order logic, which enables the encoding and automated analysis of non-trivial modal logic problems in the Isabelle/HOL proof assistant. Additionally, TPTP compliant automated theorem proving systems can be called from within Isabelle’s Sledgehammer tool for automating reasoning tasks. In the tutorial, we will apply this approach to exemplarily solve a prominent puzzle from the AI literature: the well-known wise men.

Cut-elimination for knowledge logics with interaction

In the article, multimodal logics K4n and S4n with the central agent axiom are analysed. The Hilbert type calculi are presented, then the Gentzen type calculi with cut are derived, and the proofs of thecut-eliminationtheorems are outlined. The work shows that it is possible to construct an analytical Gentzen type calculi for these logics.

Modifier Logics Based on Graded Modalities

Modifier logics are considered as generalizations of "classical" modal logics. Thus modifier logics are so-called multimodal logics. Multimodality means here that the basic logics are modal logics with graded modalities. The interpretation of modal operators is more general, too. Leibniz’s motivating semantical ideas (see [8], p. 20-21) give justification to these generalizations. Semantics of canonical frames forms the formal semantic base for modifier logics. Several modifier systems are given. A special modifier calculus is combined from some "pure" modifier logics. Creating a topological semantics to this special modifier logic may give a basis to some kind of fuzzy topology. Modifier logics of S4-type modifiers will give a graded topological interior operator systems, and thus we have a link to fuzzy topology.