Results 1  10
of
70
A Spatial Logic based on Regions and Connection
 PROCEEDINGS 3RD INTERNATIONAL CONFERENCE ON KNOWLEDGE REPRESENTATION AND REASONING
, 1992
"... 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 us ..."
Abstract

Cited by 578 (30 self)
 Add to MetaCart
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.
Actions and Events in Interval Temporal Logic
 Journal of Logic and Computation
, 1994
"... 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 rec ..."
Abstract

Cited by 240 (7 self)
 Add to MetaCart
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...
Temporal Query Languages: a Survey
, 1995
"... We define formal notions of temporal domain and temporal database, and use them to survey a wide spectrum of temporal query languages. We distinguish between an abstract temporal database and its concrete representations, and accordingly between abstract and concrete temporal query languages. We als ..."
Abstract

Cited by 107 (11 self)
 Add to MetaCart
We define formal notions of temporal domain and temporal database, and use them to survey a wide spectrum of temporal query languages. We distinguish between an abstract temporal database and its concrete representations, and accordingly between abstract and concrete temporal query languages. We also address the issue of incomplete temporal information. 1 Introduction A temporal database is a repository of temporal information. A temporal query language is any query language for temporal databases. In this paper we propose a formal notion of temporal database and use this notion in surveying a wide spectrum of temporal query languages. The need to store temporal information arises in many computer applications. Consider, for example, records of various kinds: financial [37], personnel, medical [98], or judicial. Also, monitoring data, e.g., in telecommunications network management [4] or process control, has often a temporal dimension. There has been a lot of research in temporal dat...
Timeml: Robust specification of event and temporal expressions in text
 in Fifth International Workshop on Computational Semantics (IWCS5
, 2003
"... In this paper we provide a description of TimeML, a rich specification language for event and temporal expressions in natural language text, developed in the context of the AQUAINT program on Question Answering Systems. Unlike most previous work on event annotation, TimeML captures three distinct ph ..."
Abstract

Cited by 101 (7 self)
 Add to MetaCart
In this paper we provide a description of TimeML, a rich specification language for event and temporal expressions in natural language text, developed in the context of the AQUAINT program on Question Answering Systems. Unlike most previous work on event annotation, TimeML captures three distinct phenomena in temporal markup: (1) it systematically anchors event predicates to a broad range of temporally denotating expressions; (2) it orders event expressions in text relative to one another, both intrasententially and in discourse; and (3) it allows for a delayed (underspecified) interpretation of partially determined temporal expressions. We demonstrate the expressiveness of TimeML for a broad range of syntactic and semantic contexts, including aspectual predication, modal subordination, and an initial treatment of lexical and constructional causation in text. 1
Ontological Semantics
, 2004
"... This book introduces ontological semantics, a comprehensive approach to the treatment of text meaning by computer. Ontological semantics is an integrated complex of theories, methodologies, descriptions and implementations. In ontological semantics, a theory is viewed as a set of statements determin ..."
Abstract

Cited by 90 (28 self)
 Add to MetaCart
This book introduces ontological semantics, a comprehensive approach to the treatment of text meaning by computer. Ontological semantics is an integrated complex of theories, methodologies, descriptions and implementations. In ontological semantics, a theory is viewed as a set of statements determining the format of descriptions of the phenomena with which the theory deals. A theory is associated with a methodology used to obtain the descriptions. Implementations are computer systems that use the descriptions to solve specific problems in text processing. Implementations of ontological semantics are combined with other processing systems to produce applications, such as information extraction or machine translation. The theory of ontological semantics is built as a society of microtheories covering such diverse ground as specific language phenomena, world knowledge organization, processing heuristics and issues relating to knowledge representation and implementation system architecture. The theory briefly sketched above is a toplevel microtheory, the ontological semantics theory per se. Descriptions in ontological semantics include text meaning representations, lexical entries, ontological concepts and instances as well as procedures for manipulating texts and their meanings. Methodologies in ontological semantics are sets of techniques and instructions for acquiring and
On Binary Constraint Problems
 Journal of the ACM
, 1994
"... The concepts of binary constraint satisfaction problems can be naturally generalized to the relation algebras of Tarski. The concept of pathconsistency plays a central role. Algorithms for pathconsistency can be implemented on matrices of relations and on matrices of elements from a relation algeb ..."
Abstract

Cited by 88 (2 self)
 Add to MetaCart
The concepts of binary constraint satisfaction problems can be naturally generalized to the relation algebras of Tarski. The concept of pathconsistency plays a central role. Algorithms for pathconsistency can be implemented on matrices of relations and on matrices of elements from a relation algebra. We give an example of a 4by4 matrix of infinite relations on which no iterative local pathconsistency algorithm terminates. We give a class of examples over a fixed finite algebra on which all iterative local algorithms, whether parallel or sequential, must take quadratic time. Specific relation algebras arising from interval constraint problems are also studied: the Interval Algebra, the Point Algebra, and the Containment Algebra. 1 Introduction The logical study of binary relations is classical [8], [9], [51], [52], [56], [53], [54]. Following this tradition, Tarski formulated the theory of binary relations as an algebraic theory called relation algebra [59] 1 . Constraint satis...
Modelling Topological and Metrical Properties in Physical Processes.
 eds), Proceedings 1st International Conference on the Principles of Knowledge Representation and Reasoning
, 1989
"... Developing suitable representations for formalising nontrivial domain knowledge has always been central to AI. Within Naive Physics ie. the task of encoding experiential knowledge of the world, few formal theories have appeared that exhibit formal elegance, conciseness and generality to cover ..."
Abstract

Cited by 51 (6 self)
 Add to MetaCart
Developing suitable representations for formalising nontrivial domain knowledge has always been central to AI. Within Naive Physics ie. the task of encoding experiential knowledge of the world, few formal theories have appeared that exhibit formal elegance, conciseness and generality to cover a wide variety of modelling problems. We outline a first order formalism being developed that meets these criteria. The formalism is particularly attractive in that it provides the user with the means to model either spatial and/or temporal information as required. The power of the formalism is illustrated by modelling the process of phagocytosis of the amoeba, together with an outline of how many properties of physical entities and relations between them can be modelled within a unitary framework. 1.0 Introduction The importance of representation within a formal framework has always been a central topic for discussion within AI. This has been particularly noticeable since Hayes'...
How Far Can We `C'?  Defining a `Doughnut' Using Connection Alone
 Sandewall and P. Torasso (eds), Principles of Knowledge Representation and Reasoning: Proceedings of the 4th International Conference (KR94
, 1994
"... The paper continues the work of Randell, Cohn and Cui on regionbased qualitative representations of spatial properties and relations, built on the `logic of connection' developed by Clarke. The paper shows how taxonomies of topological properties and relations can be developed, using the ..."
Abstract

Cited by 42 (8 self)
 Add to MetaCart
The paper continues the work of Randell, Cohn and Cui on regionbased qualitative representations of spatial properties and relations, built on the `logic of connection' developed by Clarke. The paper shows how taxonomies of topological properties and relations can be developed, using the single primitive `C', where C(x; y) indicates that regions x and y are `connected', meaning that their closures share at least one point. This is done by considering a specific task: deciding whether a region has the topology of a solid torus, or `doughnut', by asking questions using only terms logically derived from C. It is shown how this task could be performed under a restrictive set of assumptions about the topological properties of regions in general, and the target region in particular. These assumptions are then progressively relaxed. As this is done, the task requires the definition of successive layers of terminology, all derived ultimately from C, providing the basis ...
On Binary Constraint Networks
, 1988
"... It is wellknown that general constraint satisfaction problems (CSPs) may be reduced to the binary case (BCSPs) [Pei92]. CSPs may be represented by binary constraint networks (BCNs), which can be represented by a graph with nodes for variables for which values are to be found in the domain of intere ..."
Abstract

Cited by 38 (5 self)
 Add to MetaCart
It is wellknown that general constraint satisfaction problems (CSPs) may be reduced to the binary case (BCSPs) [Pei92]. CSPs may be represented by binary constraint networks (BCNs), which can be represented by a graph with nodes for variables for which values are to be found in the domain of interest, and edges labelled with binary relations between the values, which constrain the choice of solutions to those which satisfy the relations (e.g. [Mac77]). We formulate networks and algorithms in a general algebraic setting, that of Tarski's relation algebra [JonTar52], and obtain a parallel O(n log n) upper bound for pathconsistency, and give a class of examples on which reductiontype algorithms (which include the standard serial algorithms [Mac77, MacFre85, MohHen86] and all possible parallelisations of them) are O(n ). We then consider BCNs over various classes of relations that arise from an underlying linearly ordered set, the most wellknown being the interval algebra [All83, LadMad88.1]. There are three main consequences of the algebraic approach. Firstly, it puts the theory of BCNs on a firm (and classical) theoretical footing, enabling, for example, the complexity results. Secondly, we can apply techniques from relation algebra to show that consistency checking for a large class of relations on intervals ([All83]) is serial cubic, or parallel log time, significantly extending previous results (the problem is NPhard in general [VilKau86]). Thirdly, results are obtained via a new construction of relation algebras from other algebras which is of independent mathematical interest.
Modality in Dialogue: Planning, Pragmatics and Computation
, 1998
"... Natural language generation (NLG) is first and foremost a reasoning task. In this reasoning, a system plans a communicative act that will signal key facts about the domain to the hearer. In generating action descriptions, this reasoning draws on characterizations both of the causal properties of the ..."
Abstract

Cited by 36 (9 self)
 Add to MetaCart
Natural language generation (NLG) is first and foremost a reasoning task. In this reasoning, a system plans a communicative act that will signal key facts about the domain to the hearer. In generating action descriptions, this reasoning draws on characterizations both of the causal properties of the domain and the states of knowledge of the participants in the conversation. This dissertation shows how such characterizations can be specified declaratively and accessed efficiently in NLG. The heart of this dissertation is a study of logical statements about knowledge and action in modal logic. By investigating the prooftheory of modal logic from a logic programming point of view, I show how many kinds of modal statements can be seen as straightforward instructions for computationally manageable search, just as Prolog clauses can. These modal statements provide sufficient expressive resources for an NLG system to represent the effects of actions in the world or to model an addressee whose knowledge in some respects exceeds and in other respects falls short of its own. To illustrate the use of such statements, I describe how the SPUD sentence planner exploits a modal knowledge base to