Results 1  10
of
75
Hybrid Logics: Characterization, Interpolation and Complexity
 Journal of Symbolic Logic
, 1999
"... Hybrid languages are expansions of propositional modal languages which can refer to (or even quantify over) worlds. The use of strong hybrid languages dates back to at least [Pri67], but recent work (for example [BS98, BT98a, BT99]) has focussed on a more constrained system called H(#; @). We sho ..."
Abstract

Cited by 105 (37 self)
 Add to MetaCart
Hybrid languages are expansions of propositional modal languages which can refer to (or even quantify over) worlds. The use of strong hybrid languages dates back to at least [Pri67], but recent work (for example [BS98, BT98a, BT99]) has focussed on a more constrained system called H(#; @). We show in detail that H(#; @) is modally natural. We begin by studying its expressivity, and provide model theoretic characterizations (via a restricted notion of EhrenfeuchtFrasse game, and an enriched notion of bisimulation) and a syntactic characterization (in terms of bounded formulas). The key result to emerge is that H(#; @) corresponds to the fragment of rstorder logic which is invariant for generated submodels. We then show that H(#; @) enjoys (strong) interpolation, provide counterexamples for its nite variable fragments, and show that weak interpolation holds for the sublanguage H(@). Finally, we provide complexity results for H(@) and other fragments and variants, and sh...
Internalizing Labelled Deduction
 Journal of Logic and Computation
, 2000
"... This paper shows how to internalize the Kripke satisfaction denition using the basic hybrid language, and explores the proof theoretic consequences of doing so. As we shall see, the basic hybrid language enables us to transfer classic Gabbaystyle labelled deduction methods from the metalanguage to ..."
Abstract

Cited by 77 (21 self)
 Add to MetaCart
This paper shows how to internalize the Kripke satisfaction denition using the basic hybrid language, and explores the proof theoretic consequences of doing so. As we shall see, the basic hybrid language enables us to transfer classic Gabbaystyle labelled deduction methods from the metalanguage to the object language, and to handle labelling discipline logically. This internalized approach to labelled deduction links neatly with the Gabbaystyle rules now widely used in modal Hilbertsystems, enables completeness results for a wide range of rstorder denable frame classes to be obtained automatically, and extends to many richer languages. The paper discusses related work by Jerry Seligman and Miroslava Tzakova and concludes with some reections on the status of labelling in modal logic. 1 Introduction Modern modal logic revolves around the Kripke satisfaction relation: M;w ': This says that the model M satises (or forces, or supports) the modal formula ' at the state w in M....
The Complexity of Reasoning with Cardinality Restrictions and Nominals in Expressive Description Logics
 JOURNAL OF ARTIFICIAL INTELLIGENCE RESEARCH
, 2000
"... We study the complexity of the combination of the Description Logics ALCQ and ALCQI with a terminological formalism based on cardinality restrictions on concepts. These combinations can naturally be embedded into C², the two variable fragment of predicate logic with counting quantifiers, which yi ..."
Abstract

Cited by 61 (0 self)
 Add to MetaCart
We study the complexity of the combination of the Description Logics ALCQ and ALCQI with a terminological formalism based on cardinality restrictions on concepts. These combinations can naturally be embedded into C², the two variable fragment of predicate logic with counting quantifiers, which yields decidability in NExpTime. We show that this approach leads to an optimal solution for ALCQI, as ALCQI with cardinality restrictions has the same complexity as C² (NExpTimecomplete). In contrast, we show that for ALCQ, the problem can be solved in ExpTime. This result is obtained by a reduction of reasoning with cardinality restrictions to reasoning with the (in general weaker) terminological formalism of general axioms for ALCQ extended with nominals . Using the same reduction, we show that, for the extension of ALCQI with nominals, reasoning with general axioms is a NExpTimecomplete problem. Finally, we sharpen this result and show that pure concept satisfiability for A...
A Modal Perspective on the Computational Complexity of Attribute Value Grammar
, 1992
"... Many of the formalisms; used in Attribute Value grammar are notational variants of languages of propositional modal logic,. and testing whether two Attribute Value descriptions unify amounts to testing for modal satisfiability. In this paper we put this. observation to work. We study the complexit ..."
Abstract

Cited by 43 (7 self)
 Add to MetaCart
Many of the formalisms; used in Attribute Value grammar are notational variants of languages of propositional modal logic,. and testing whether two Attribute Value descriptions unify amounts to testing for modal satisfiability. In this paper we put this. observation to work. We study the complexity of the satisfiability problem for nine modal languages which mirror different aspects of AVS description formalisms, including the ability to express reeintrancy, the ability to express generalisations, and the ability to express recursive constraints. Two mail techniques axe used: either Kripke models with desirable properties are constructed, or modalities are used to simulate fragments of Propositional Dynamic Logic. Further possibilities for the application of modal logic in computational linguistics are noted
Hierarchies of Modal and Temporal Logics with Reference Pointers
 Journal of Logic, Language and Information
, 1995
"... . We introduce and study hierarchies of extensions of the propositional modal and temporal languages with pairs of new syntactic devices: "point of reference  reference pointer" which enable semantic references to be made within a formula. We propose three different but equivalent sema ..."
Abstract

Cited by 43 (2 self)
 Add to MetaCart
. We introduce and study hierarchies of extensions of the propositional modal and temporal languages with pairs of new syntactic devices: "point of reference  reference pointer" which enable semantic references to be made within a formula. We propose three different but equivalent semantics for the extended languages, discuss and compare their expressiveness. The languages with reference pointers are shown to have great expressive power (especially when their frugal syntax is taken into account), perspicuous semantics, and simple deductive systems. For instance, Kamp's and Stavi's temporal operators, as well as nominals (names, clock variables), are definable in them. The universal validity in these languages is proved undecidable. The basic modal and temporal logics with reference pointers are uniformly axiomatized and strong completeness theorem is proved for them and extended to some classes of their extensions. Key words: Modal and Temporal Logics, Reference Pointers, Expressi...
Hybrid Logics
"... This chapter provides a modern overview of the field of hybrid logic. Hybrid logics are extensions of standard modal logics, involving symbols that name individual states in models. The first results that are nowadays considered as part of the field date back to the early work of Arthur ..."
Abstract

Cited by 41 (11 self)
 Add to MetaCart
This chapter provides a modern overview of the field of hybrid logic. Hybrid logics are extensions of standard modal logics, involving symbols that name individual states in models. The first results that are nowadays considered as part of the field date back to the early work of Arthur
Hybrid languages and temporal logic
 Logic J. IGPL
, 1999
"... Hybridization is a method invented by Arthur Prior for extending the expressive power of modal languages. Although developed in interesting ways by Robert Bull, and by the So a school (notably, George Gargov, Valentin Goranko, Solomon Passy and Tinko Tinchev), the method remains little known. In our ..."
Abstract

Cited by 40 (16 self)
 Add to MetaCart
Hybridization is a method invented by Arthur Prior for extending the expressive power of modal languages. Although developed in interesting ways by Robert Bull, and by the So a school (notably, George Gargov, Valentin Goranko, Solomon Passy and Tinko Tinchev), the method remains little known. In our view this has deprived temporal logic of a valuable tool. The aim of the paper is to explain why hybridization is useful in temporal logic. We make two major points, the rst technical, the second conceptual. First, we showthathybridization gives rise to wellbehaved logics that exhibit an interesting synergy between modal and classical ideas. This synergy, obvious for hybrid languages with full rstorder expressive strength, is demonstrated for a weaker local language capable of de ning the Until operator � we provide a minimal axiomatization, and show that in a wide range of temporally interesting cases extended completeness results can be obtained automatically. Second, we argue that the idea of sorted atomic symbols which underpins the hybrid enterprise can be developed further. To illustrate this, we discuss the advantages and disadvantages of a simple hybrid language which can quantify over paths. 1
Derivation rules as antiaxioms in modal logic
 Journal of Symbolic Logic
, 1993
"... Abstract. We discuss a ‘negative ’ way of defining frame classes in (multi)modal logic, and address the question whether these classes can be axiomatized by derivation rules, the ‘nonξ rules’, styled after Gabbay’s Irreflexivity Rule. The main result of this paper is a metatheorem on completeness ..."
Abstract

Cited by 40 (2 self)
 Add to MetaCart
Abstract. We discuss a ‘negative ’ way of defining frame classes in (multi)modal logic, and address the question whether these classes can be axiomatized by derivation rules, the ‘nonξ rules’, styled after Gabbay’s Irreflexivity Rule. The main result of this paper is a metatheorem on completeness, of the following kind: If Λ is a derivation system having a set of axioms that are special Sahlqvist formulas, and Λ+ is the extension of Λ with a set of nonξ rules, then Λ+ is strongly sound and complete with respect to the class of frames determined by the axioms and the rules.
Products of Modal Logics, Part 1
 LOGIC JOURNAL OF THE IGPL
, 1998
"... The paper studies manydimensional modal logics corresponding to products of Kripke frames. It proves results on axiomatisability, the finite model property and decidability for product logics, by applying a rather elaborated modal logic technique: pmorphisms, the finite depth method, normal forms, ..."
Abstract

Cited by 36 (1 self)
 Add to MetaCart
The paper studies manydimensional modal logics corresponding to products of Kripke frames. It proves results on axiomatisability, the finite model property and decidability for product logics, by applying a rather elaborated modal logic technique: pmorphisms, the finite depth method, normal forms, filtrations. Applications to first order predicate logics are considered too. The introduction and the conclusion contain a discussion of many related results and open problems in the area.
Modal Logic and Attribute Value Structures
 University of Amsterdam, ITLI
, 1993
"... This paper shows that there is a close correspondence between propositional modal logic and the AV formalisms of computational linguistics. A particularly important aspect of this relationship is that unification can be seen as testing for modal satisfiability. The paper considers three modal langua ..."
Abstract

Cited by 31 (9 self)
 Add to MetaCart
This paper shows that there is a close correspondence between propositional modal logic and the AV formalisms of computational linguistics. A particularly important aspect of this relationship is that unification can be seen as testing for modal satisfiability. The paper considers three modal languages  L, L N and L KR  and for each of them describes the correspondence involved and proves results concerning completeness, decidability and expressive power. This paper examines the relationship between various languages of modal logic and an approach to the speci cation and processing of natural language grammars currently popular in computational linguistics. This approach is the use of Attribute Value formalisms, and the main aims of the paper are to show that the most common Attribute Value formalisms are nothing but languages of propositional modal logic, and to establish the basic logical theory of the languages concerned. The first section is an overview of the main ideas...