This volume contains a selection of papers presented at a Seminar on Intensional Logic held at the University of Amsterdam during the period September 1990-May 1991. Modal logic, either as a topic or as a tool, is common to most of the papers in this volume. A number of the papers are con­ cerned with what may be called well-known or traditional modal systems, but, as a quick glance through this volume will reveal, this by no means implies that they walk the beaten tracks. In­ deed, such contributions display new directions, new results, and new techniques to obtain familiar results. Other papers in this volume are representative examples of a current trend in modal logic: the study of extensions or adaptations of the standard sys­ tems that have been introduced to overcome various shortcomings of the latter, especially their limited expressive power. Finally, there is another major theme that can be discerned in the vol­ ume, a theme that may be described by the slogan 'representing changing information. ' Papers falling under this heading address long-standing issues in the area, or present a systematic approach, while a critical survey and a report contributing new techniques are also included. The bulk of the papers on pure modal logic deal with theoreti­ calor even foundational aspects of modal systems.

Inhalt

Preface. Beyond Accessibility: Functional Models for Modal Logic; J. van Benthem. Modal Logic and Attribute Value Structures; P. Blackburn. Interpreting Modal Natural Deduction in Type Theory; T. Borghuis. Modal Translations in K and D; K. Dosen. Logical Omniscience and Inconsistent Belief; J.O.M. Jaspars. Cautious Backtracking in Truth Maintenance Systems; C. Jonker. How Completeness and Correspondence Theory got Married; M. Kracht. Dyadic Modalities and Lambek Calculus; D. Roorda. A Logic with Progressive Tenses; V. Shehtman. The Complexity of Propositional Tense Logics; E. Spaan. On Total Awareness Logics; E. Thijsse. Completeness via Completeness: Since and Until; Y. Venema. The Feasibility of Defeat in Defeasible Reasoning; G. Vreeswijk. Index.