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Toward Principles for the Design of Ontologies Used for Knowledge Sharing
 IN FORMAL ONTOLOGY IN CONCEPTUAL ANALYSIS AND KNOWLEDGE REPRESENTATION, KLUWER ACADEMIC PUBLISHERS, IN PRESS. SUBSTANTIAL REVISION OF PAPER PRESENTED AT THE INTERNATIONAL WORKSHOP ON FORMAL ONTOLOGY
, 1993
"... Recent work in Artificial Intelligence is exploring the use of formal ontologies as a way of specifying contentspecific agreements for the sharing and reuse of knowledge among software entities. We take an engineering perspective on the development of such ontologies. Formal ontologies are viewed a ..."
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Cited by 1340 (3 self)
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Recent work in Artificial Intelligence is exploring the use of formal ontologies as a way of specifying contentspecific agreements for the sharing and reuse of knowledge among software entities. We take an engineering perspective on the development of such ontologies. Formal ontologies are viewed as designed artifacts, formulated for specific purposes and evaluated against objective design criteria. We describe the role of ontologies in supporting knowledge sharing activities, and then present a set of criteria to guide the development of ontologies for these purposes. We show how these criteria are applied in case studies from the design of ontologies for engineering mathematics and bibliographic data. Selected design decisions are discussed, and alternative representation choices and evaluated against the design criteria.
A Framework for KnowledgeBased Temporal Abstraction
, 1997
"... A new domainindependent knowledgebased inference structure is presented, specific to the task of abstracting higherlevel concepts from timestamped data. The framework includes a model of time, parameters, events, and contexts. A formal specification of a domains temporalabstraction knowledge su ..."
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Cited by 131 (37 self)
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A new domainindependent knowledgebased inference structure is presented, specific to the task of abstracting higherlevel concepts from timestamped data. The framework includes a model of time, parameters, events, and contexts. A formal specification of a domains temporalabstraction knowledge supports acquisition, maintenance, reuse, and sharing of that knowledge.
KnowledgeBased Temporal Abstraction in Clinical Domains
, 1996
"... We have defined a knowledgebased framework for solving the task of creating abstract, intervalbased concepts from timestamped clinical datathe knowledgebased temporalabstraction (KBTA) method. The KBTA method decomposes the temporalabstraction task into five tasks; a formal mechanism is propose ..."
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Cited by 92 (32 self)
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We have defined a knowledgebased framework for solving the task of creating abstract, intervalbased concepts from timestamped clinical datathe knowledgebased temporalabstraction (KBTA) method. The KBTA method decomposes the temporalabstraction task into five tasks; a formal mechanism is proposed for solving each subtask. The KBTA framework emphasizes the explicit representation of the knowledge required for abstraction of timeoriented clinical data, and facilitates its acquisition, maintenance, reuse, and sharing. The RSUM system implements the KBTA method. We tested RSUM in several clinical domains in which the task of monitoring patients is prominent. In particular, we tested the KBTA framework in the domain of monitoring patients who have insulindependent diabetes. We acquired from a diabetestherapy expert a diabetestherapy temporalabstraction knowledge base. Two diabetestherapy experts (including the first one) created temporal abstractions relevant to the therapymonitoring task from about 800 points of data from cases of diabetic patients. The RSUM system generated about 80% of the abstractions agreed by both experts; about 97% of the overall generated abstractions were valid. We discuss the advantages and limitations of the current architecture.
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 ..."
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Cited by 87 (2 self)
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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...
A representation for collections of temporal intervals
 In Proceedings of AAAI
, 1986
"... Temporal representation and reasoning are necessary components of systems that consider events that occur in the real world. This work explores ways of considering collections of intervals of time. This line of research is motivated by related work being done by our research group on appointment sch ..."
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Cited by 64 (0 self)
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Temporal representation and reasoning are necessary components of systems that consider events that occur in the real world. This work explores ways of considering collections of intervals of time. This line of research is motivated by related work being done by our research group on appointment scheduling and time management. Natural language expressions that refer to collections of intervals are used naturally and routinely in these contexts, and an effective means of representing them is essential. Previous studies, which considered intervals primarily in isolation, have difficulties in representing some classes of expressions. This occurs not only with expressions that explicitly refer to collections of intervals, such as “the first of every month, ” but also with expressions that do so only
Taxonomies of Logically Defined Qualitative Spatial Relations
 IN N. GUARINO AND R. POLI (EDS), FORMAL ONTOLOGY IN CONCEPTUAL ANALYSIS AND KNOWLEDGE REPRESENTATION
, 1994
"... This paper develops a taxonomy of qualitative spatial relations for pairs of regions, which are all logically defined from two primitive (but axiomatised) notions. The first primitive is the notion of two regions being connected, which allows eight jointly exhaustive and pairwise disjoint relations ..."
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Cited by 48 (21 self)
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This paper develops a taxonomy of qualitative spatial relations for pairs of regions, which are all logically defined from two primitive (but axiomatised) notions. The first primitive is the notion of two regions being connected, which allows eight jointly exhaustive and pairwise disjoint relations to be defined. The second primitive is the convex hull of a region which allows many more relations to be defined. We also consider the development of the useful notions of composition tables for the defined relations and networks specifying continuous transitions between pairs of regions. We conclude by discussing what kind of criteria to apply when deciding how fine a taxonomy to create.
Dynamic Temporal Interpretation Contexts for Temporal Abstraction
, 1995
"... Temporal abstraction is the task of abstracting higherlevel concepts from timestamped data in a contextsensitive manner. We have developed and implemented a formal knowledgebased framework for decomposing and solving that task that supports acquisition, maintenance, reuse, and sharing of temporal ..."
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Cited by 35 (21 self)
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Temporal abstraction is the task of abstracting higherlevel concepts from timestamped data in a contextsensitive manner. We have developed and implemented a formal knowledgebased framework for decomposing and solving that task that supports acquisition, maintenance, reuse, and sharing of temporalabstraction knowledge.
Symbolic Representation of Userdefined Time Granularities
 Annals of Mathematics and Artificial Intelligence
, 1999
"... In the recent literature on time representation, an effort has been made to characterize the notion of time granularity and the relationships between granularities, in order to have a common framework for their specification, and to allow the interoperability of systems adopting different time granu ..."
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Cited by 31 (3 self)
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In the recent literature on time representation, an effort has been made to characterize the notion of time granularity and the relationships between granularities, in order to have a common framework for their specification, and to allow the interoperability of systems adopting different time granularities. This paper considers the mathematical characterization of finite and periodical time granularities, and it identifies a userfriendly symbolic formalism which captures exactly that class of granularities. This is achieved by a formal analysis of the expressiveness of wellknown symbolic representation formalisms. 1. Introduction There is a wide agreement in the AI and database community on the requirement for a data/knowledge representation system of supporting standard as well as userdefined time granularities. Examples of standard time granularities are days, weeks, months, while user defined granularities may include businessweeks, tradingdays, workingshifts, schoolterms, wi...
The Logic of Time Representation
, 1987
"... This investigation concerns representations of time by means of intervals, stemming from work of Allen [All83] and van Benthem [vBen83]. Allen described an Interval Calculus of thirteen binary relations on convex intervals over a linear order (the real numbers). He gave a practical algorithm for che ..."
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Cited by 29 (1 self)
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This investigation concerns representations of time by means of intervals, stemming from work of Allen [All83] and van Benthem [vBen83]. Allen described an Interval Calculus of thirteen binary relations on convex intervals over a linear order (the real numbers). He gave a practical algorithm for checking the consistency of a subclass of Boolean constraints. First, we describe a completeness theorem for Allen's calculus, in its corresponding formulation as a firstorder theory LM . LM is countably categorical, and axiomatises the complete theory of intervals over a dense unbounded linear order. Its only countable model up to isomorphism is the nontrivial intervals over the rational numbers. Algorithms are given for quantiferelimination, consistency checking, and satisfaction of arbitrary firstorder formulas in the Interval Calculus. A natural countable model of the calculus is presented, the TUS , in which clock and calendartime may be represented in a straightforward way. Allen an...
Using Hindsight in Medical Decision Making
 Proceedings, Thirteenth Annual Symposium on Computer Applications in Medical Care
, 1990
"... As the clinical picture of a patient evolves over time, more information becomes available. Certain procedures require time to perform, causing a delay between the time when the tests are ordered and when the results are available. Furthermore, as the patient's condition changes over time, serial me ..."
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Cited by 25 (1 self)
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As the clinical picture of a patient evolves over time, more information becomes available. Certain procedures require time to perform, causing a delay between the time when the tests are ordered and when the results are available. Furthermore, as the patient's condition changes over time, serial measurements can be made. The availability of more data allows a more accurate assessment of the patient. Uncertainties, guesses or errors that were made early in the clinical course of patient care can also be identified and resolved when more information is available. Reasoning with a stream of data that changes over time presents a challenge to the designers of expert systems. The use of hindsight in expert systems requires that appropriate attention be paid to the temporal relations of the data and that care is exercised in revising decisions. I present a datadependency system, the Temporal Control Structure (tcs), designed to support reasoning with data changing over time and show how it...