This paper addresses the problem of establishing temporal properties of programs written in languages, such as Java, that make extensive use of the heap to allocate--- and deallocate---new objects and threads. Establishing liveness properties is a particularly hard challenge. One of the crucial obstacles is that heap locations have no static names and the number of heap locations is unbounded. The paper presents a framework for the verification of Java-like programs. Unlike classical model checking, which uses propositional temporal logic, we use first-order temporal logic to specify temporal properties of heap evolutions; this logic allows domain changes to be expressed, which permits allocation and deallocation to be modelled naturally. The paper also presents an abstract-interpretation algorithm that automatically verifies temporal properties expressed using the logic.

This book deals with the semantics of natural language expressions that are commonly taken to refer to individuals: pronouns, definite descriptions and proper names. It claims, contrary to previous theorizing, that they all have a common syntax and semantics, roughly that which is currently associated by philosophers and linguists with definite descriptions as construed in the tradition of Frege. As well as advancing this proposal, I hope to achieve at least one other aim, that of urging semanticists dealing with pronoun interpretation, in particular donkey anaphora, to consider a wider range of theories at all times than is sometimes done at present. I am thinking particularly of the gulf that seems to have emerged between those who practice some version of dynamic semantics (including DRT) and those who eschew this approach and rely on some version of the E-type analysis for donkey anaphora (if they consider this phenomenon at all). In my opinion there is too little work directly comparing the claims of these two schools (for that is what they amount to) and testing them against the data in the way that any two rival theories might be tested. (Irene Heim’s 1990 article in Linguistics and Philosophy does this, and

In order to provide a principled foundation for the study of discourse, in this paper we propose answers to three basic questions: What are the atomic units of discourse? What kind of structures can be built from the elementary units? How do we interpret the resulting structures semantically? Inferences and the correct interpretation of deixis and anaphors in discourse depend upon both structural and semantic accessibility relations. Structurally, we argue, discourse is context free and accessibility is determined by the coordination and subordination relations specified by the model of discourse presented here. Semantically, accessibility is controlled by relations among a number of modal contexts (interaction, speech event, genre unit, modality, polarity, and point of view) which determine the discourse world relative to which each primitive discourse unit is interpreted. To demonstrate the validity of our approach, the linguistic discourse model developed here is applied to a problem concerning the distribution of a discourse particle in Mocho and to various problems of discourse interpretation.

This is an attempt at reviving Kneale's version of the description theory of names, which says that a proper name is synonymous with a definite description of the form 'the individual named so-and-so'. To begin with, I adduce a wide range of observations to show that names and overt definites are alike in all relevant respects. I then turn to Kripke's main objection against Kneale's proposal, and endeavour to refute it. In the remainder of the paper I elaborate on Kneale's analysis, adopting a theory of presupposition proposed by van der Sandt.

Two recent lines of database research. proceeding independently, have been concerned with providing a richer, more intuitive view of information at the user level. Historical database research has focused on ways to provide users with a view of information anchored and evolving in the temporal dimension. Object-oriented database research focuses on encapsulating both the structure and the behavior of the objects that users intend to model. In this paper we explore how these two lines of research might be brought together. providing to the user the representation and management of objects in tzme. I.

This project continues our interdisciplinary research into computational and cognitive aspects of narrative comprehension. Our ultimate goal is the development of a computational theory of how humans understand narrative texts. The theory will be informed by joint research from the viewpoints of linguistics, cognitive psychology, the study of language acquisition, literary theory, geography, philosophy, and artificial intelligence. The linguists, literary theorists, and geographers in our group are developing theories of narrative language and spatial understanding that are being tested by the cognitive psychologists and language researchers in our group, and a computational model of a reader of narrative text is being developed by the AI researchers, based in part on these theories and results and in part on research on knowledge representation and reasoning. This proposal describes the knowledge-representation and natural-language-processing issues involved in the computational implementation of the theory; discusses a contrast between communicative and narrative uses of language and of the relation of the narrative text to the story world it describes; investigates linguistic, literary, and hermeneutic dimensions of our research; presents a computational investigation of subjective sentences and reference in narrative; studies children’s acquisition of the ability to take third-person perspective in their own storytelling; describes the psychological validation of various linguistic devices; and examines how readers develop an understanding of the geographical space of a story. This report is a longer

First-order modal logic is very much under current development, with many di#erent semantics proposed. The use of rigid objects goes back to Saul Kripke. More recently several semantics based on counterparts have been examined, in a development that goes back to David Lewis.

The combination of first-order epistemic logic and formal cryptography offers a potentially very powerful framework for security protocol verification. In this article, we address two main challenges towards such a combination; First, the expressive power, specifically the epistemic modality, needs to receive concrete computational justification. Second, the logic must be shown to be, in some sense, formally tractable. Addressing the first challenge, we provide a generalized Kripke semantics that uses permutations on the underlying domain of cryptographic messages to reflect agents ’ limited computational power. Using this approach, we obtain logical characterizations of important concepts of knowledge in the security protocol literature, namely Dolev-Yao style message deduction and static equivalence. Answering the second challenge, we exhibit an axiomatization which is sound and complete relative to the underlying theory of cryptographic terms, and to an omega rule for quantifiers. The axiomatization uses largely standard axioms and rules from first-order modal logic. In addition, it includes some novel axioms for the interaction between knowledge and cryptography. To illustrate the usefulness of the logic we consider protocol examples using mixes, a Crowds style protocol, and electronic payments. Furthermore, we provide embedding results for BAN and SVO. 1

Formal ontology, as the science of the formal relations that structure reality as a whole, aims at a theory of categories corresponding to the most general features of possible objects, whether existing or non-existing. The present paper is an attempt to summarise and extend recent research in analytical metaphysics in a formalised theory of objects. Existence is characterised as a formal property, suggesting that the use of quantifiers alone does not involve any existential assumptions about the objects quantified over. However, the only non-existing objects allowed for in the present account are real or objective possibilities. De re modalities as well as ontological dependence are defined on the basis of a counterpart-theoretic specification of possibilia. The present framework allows for necessary and non-relative identity as well as for a granular parthood relationship satisfying the thesis of composition as partial identity. The paper culminates in the formalisation of an Aristotelian four-category ontology allowing for universals and particulars, substances and particularised properties; in this context, the redundance of higher-order material universals as well as moderate haecceitism is argued for. After a short analysis of relationality and extrinsicness, a theory of spatial and temporal objects is sketched and a temporal counterpart theory is proposed as a solution to the problem of temporary intrinsics. The paper concludes with some general remarks on the relation between ontology and the theory of subjectivity, defending a modal approach to consciousness and a counterpart theoretic analysis of intentionality.

We introduce a symmetry reduction technique for model checking temporal-epistemic properties of multi-agent systems defined in the mainstream interpreted systems framework. The technique, based on counterpart semantics, aims to reduce the set of initial states that need to be considered in a model. We present theoretical results establishing that there are neither false positives nor false negatives in the reduced model. We evaluate the technique by presenting the results of an implementation tested against two well known applications of epistemic logic, the muddy children and the dining cryptographers. The experimental results obtained confirm that the reduction in model checking time can be dramatic, thereby allowing for the verification of hitherto intractable systems. 1