We describe an interval logic for reasoning about space. The logic simplifies an earlier theory developed by Randell and Cohn, and that of Clarke upon which the former was based. The theory supports a simpler ontology, has fewer defined functions and relations, yet does not suffer in terms of its useful expressiveness. An axiomatisation of the new theory and a comparison with the two original theories is given.

A generalization of Allen's interval-based approach to temporal reasoning is presented. The notion of `conceptual neighborhood' of qualitative relations between events is central to the presented approach. Relations between semi-intervals rather than intervals are used as the basic units of knowledge. Semi-intervals correspond to temporal beginnings or endings of events. We demonstrate the advantages of reasoning on the basis of semi-intervals: 1) semi-intervals are rather natural entities both from a cognitive and from a computational point of view; 2) coarse knowledge can be processed directly; computational effort is saved; 3) incomplete knowledge about events can be fully exploited; 4) incomplete inferences made on the basis of complete knowledge can be used directly for further inference steps; 5) there is no trade-off in computational strength for the added flexibility and efficiency; 6) for a natural subset of Allen's algebra, global consistency can be guaranteed in polynomial time; 7) knowledge about relations between events can be represented much more compactly.

We present a representation of events and action based on interval temporal logic that is significantly more expressive and more natural than most previous AI approaches. The representation is motivated by work in natural language semantics and discourse, temporal logic, and AI planning and plan recognition. The formal basis of the representation is presented in detail, from the axiomatization of time periods to the relationship between actions and events and their effects. The power of the representation is illustrated by applying it to the axiomatization and solution of several standard problems from the AI literature on action and change. An approach to the frame problem based on explanation closure is shown to be both powerful and natural when combined with our representational framework. We also discuss features of the logic that are beyond the scope of many traditional representations, and describe our approach to difficult problems such as external events and simultaneous action...

: In certain areas of artificial intelligence there is need to represent continuous change and to make statements that are interpreted with respect to time intervals rather than time points. To this end we develop a modal temporal logic based on time intervals, a logic which can be viewed as a generalization of pointbased modal temporal logic. We discuss related logics, give an intuitive presentation of the new logic, and define its formal syntax and semantics. We make no assumption about the underlying nature of time, allowing it to be discrete (such as the natural numbers) or continuous (such as the rationals or the reals), linear or branching, complete (such as the reals) or not (such as the rationals). We show, however, that there are formulas in the logic that allow us to distinguish all these situations. We also give a translation of our logic into first-order logic, which allows us to apply some results on first-order logic to our modal one. Finally, we consider the difficulty o...

Abstract–Multimedia data often have time dependencies that must be satisfied at presentation time. To support a general-purpose multimedia information system, these timing relationships must be managed to provide utility to both the data presentation system and the multimedia author. In this paper we propose new conceptual models for capturing these timing relationships and managing them as part of a database. Specifically, we introduce and define n-ary and reverse temporal relations along with their temporal constraints. These new relations are a generalization of our earlier temporal models and establish the basis for conceptual database structures and temporal access control algorithms to facilitate forward, reverse, and partial-interval evaluation during multimedia object playout. The proposed relations are defined to ensure a property of monotonically increasing playout deadlines to facilitate both real-time deadline-driven playout scheduling or optimistic interval-based process playout. Furthermore, we show a translation of the conceptual models to a structure suitable for a relational database.

The notion of time is ubiquitous in any activity that requires intelligence. In particular, several important notions like change, causality, action are described in terms of time. Therefore, the representation of time and reasoning about time is of crucial importance for many Artificial Intelligence systems. Specifically during the last 10 years, it has been attracting the attention of many AI researchers. In this survey, the results of this work are analysed. Firstly, Temporal Reasoning is defined. Then, the most important representational issues which determine a Temporal Reasoning approach are introduced: the logical form on which the approach is based, the ontology (the units taken as primitives, the temporal relations, the algorithms that have been developed,. . . ) and the concepts related with reasoning about action (the representation of change, causality, action,. . . ). For each issue the different choices in the literature are discussed. 1 Introduction The notion of time i...

Abstract–The synchronization problem for audio/visual reproduction has consumed engi-neers since the advent of recorded audio and images and the first multimedia productions. As computers have evolved to support programmed reproduction of multimedia information, the complexity but not the character or interest have changed. In the digital domain, synchro-nization problems exist due to data distribution and communications, random events caused by human-computer interaction, and general computer and communications performance limitations. This rich research domain has led to numerous approaches to the modeling and execution of multimedia synchronization scenarios. Unfortunately, these approaches are difficult to compare and evaluate due to their varied theoretical bases and modeling techniques. In this paper we develop a uniform, theoretical foundation for discussing multimedia syn-chronization and temporal specification. We propose a temporal reference framework and use it to compare existing temporal specification schemes and their relationships to multime-dia synchronization. The ensuing comparison of existing specification and synchronization techniques demonstrates the utility of the framework.

This dissertation describes the formal foundations and implementation of a commonsense, mixed-initiative plan reasoning system. By "plan reasoning" I mean the complete range of cognitive tasks that people perform with plans including, for example, plan construction (planning), plan recognition, plan evaluation and comparison, and plan repair (replanning), among other things. "Mixed-initiative" means that several participants can each make contributions to the plan under development through some form of communication. "Commonsense" means that the system represents plans and their constituents at a level that is "natural" to us in the sense that they can be described and discussed in language. In addition, the reasoning that the system performs includes those conclusions that we would take to be sanctioned by common sense, including especially those conclusions that are defeasible given additional knowledge or time spent reasoning. The main theses of this dissertation are the following: ...

We propose a new model for structured temporal composition of interactive dynamic multimedia presentations. It extends the notion of basic media segments to include executable code, live feeds, and links. The model is based on Interval Expressions that involve media segments of unknown duration. 1. Introduction Multimedia representation and computing have made significant progress during last several years. However, the advances have not led to satisfactory proposals for rich dynamic adaptive story environments [3]. Existing models of multimedia presentations allow static composition of different media having inherent temporal behavior such as video and audio. Temporal composition defines synchronization among media segments according to some static temporal scenario. Usually, a presentation is played back linearly with little (simple Temporal Access Control functions) or no user control over the flow of presentation. In opposition to the traditional multimedia presentations, we are ...

Time is fundamental in representing and reasoning about changing domains. A proper temporal representation requires characterizing two notions: (1) time itself, and (2) temporal incidence, i.e. the domainindependent properties for the truth-value of fluents and events throughout time. There are some problematic issues such as the expression of instantaneous events and instantaneous holding of fluents, the specification of the properties for the temporal holding of fluents and the Dividing Instant Problem. This paper presents a theory of time and temporal incidence which is more natural than its predecessors and satisfactorily addresses the issues above. Our theory of time, called IP, is based on having instants and periods at equal level. We define a theory of temporal incidence upon it whose main original feature is the distinction between continuous and discrete fluents. 1 Introduction In order for an intelligent system to interact with the real world it needs to be able to reason...