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136
Predicting the Drape of Woven Cloth Using Interacting Particles
, 1994
"... We demonstrate a physicallybased technique for predicting the drape of a wide variety of woven fabrics. The approach exploits a theoretical model that explicitly represents the microstructure of woven cloth with interacting particles, rather than utilizing a continuum approximation. By testing a cl ..."
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Cited by 144 (5 self)
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We demonstrate a physicallybased technique for predicting the drape of a wide variety of woven fabrics. The approach exploits a theoretical model that explicitly represents the microstructure of woven cloth with interacting particles, rather than utilizing a continuum approximation. By testing a cloth sample in a Kawabata fabric testing device, we obtain data that is used to tune the model's energy functions, so that it reproduces the draping behavior of the original material. Photographs, comparing the drape of actual cloth with visualizations of simulation results, show that we are able to reliably model the unique largescale draping characteristics of distinctly different fabric types. iii Figure 1.1: Draping cloth objects 1 Introduction The vast number of uses for cloth are mirrored in the extraordinary variety of types of woven fabrics. These range from the most exquisite fine silks, to the coarsest of burlaps, and are woven from such diverse fibers as natural wool and synth...
Racer: A Core Inference Engine for the Semantic Web
, 2003
"... In this paper we describe Racer, which can be considered as a core inference engine for the semantic web. The Racer inference server o#ers two APIs that are already used by at least three di#erent network clients, i.e., the ontology editor OilEd, the visualization tool RICE, and the ontology dev ..."
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Cited by 114 (0 self)
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In this paper we describe Racer, which can be considered as a core inference engine for the semantic web. The Racer inference server o#ers two APIs that are already used by at least three di#erent network clients, i.e., the ontology editor OilEd, the visualization tool RICE, and the ontology development environment Protege 2. The Racer server supports the standard DIG protocol via HTTP and a TCP based protocol with extensive query facilities. Racer currently supports the web ontology languages DAML+OIL, RDF, and OWL.
Offering a PrecisionPerformance Tradeoff for Aggregation Queries over Replicated Data
, 2000
"... Strict consistency of replicated data is infeasible or not required by many distributed applications, so current systems often permit stale replication,inwhich cached copies of data values are allowed to become out of date. Queries over cached data return an answer quickly, but the stale answer ..."
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Cited by 104 (8 self)
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Strict consistency of replicated data is infeasible or not required by many distributed applications, so current systems often permit stale replication,inwhich cached copies of data values are allowed to become out of date. Queries over cached data return an answer quickly, but the stale answer may be unboundedly imprecise. Alternatively, queries over remote master data return a precise answer, but with potentially poor performance. To bridge the gap between these two extremes, we propose a new class of replication systems called TRAPP (Tradeoff in Replication Precision and Performance). TRAPP systems give each user finegrained control over the tradeoff between precision and performance: Caches store ranges that are guaranteed to bound the current data values, instead of storing stale exact values. Users supply a quantitative precision constraint along with each query. To answer a query, TRAPP systems automatically select a combination of locally cached bounds and exact master data stored remotely to deliver a bounded answer consisting of a range that is no wider than the specified precision constraint, that is guaranteed to contain the precise answer, and that is computed as quickly as possible. This paper defines the architecture of TRAPP replication systems and covers some mechanics of caching data ranges. It then focuses on queries with aggregation, presenting optimization algorithms for answering queries with precision constraints, and reporting on performance experiments that demonstrate the finegrained control of the precisionperformance tradeoff offered by TRAPP systems.
Automatic Structures
 IN PROC. 15TH IEEE SYMP. ON LOGIC IN COMPUTER SCIENCE
, 1999
"... We study definability and complexity issues for automatic and wautomatic structures. These are, in general, infinite structures but they can be finitely presented by a collection of automata. Moreover, they admit effective (in fact automatic) evaluation of all firstorder queries. Therefore, automa ..."
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Cited by 102 (7 self)
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We study definability and complexity issues for automatic and wautomatic structures. These are, in general, infinite structures but they can be finitely presented by a collection of automata. Moreover, they admit effective (in fact automatic) evaluation of all firstorder queries. Therefore, automatic structures provide an interesting framework for extending many algorithmic and logical methods from finite structures to infinite ones. We explain the notion of (w)automatic structures, give examples, and discuss the relationship to automatic groups. We determine the complexity of model checking and query evaluation on automatic structures for fragments of firstorder logic. Further, we study closure properties and definability issues on automatic structures and present a technique for proving that a structure is not automatic. We give modeltheoretic characterisations for automatic structures via interpretations. Finally we discuss the composition theory of automatic structures and pro...
Constraint Programming and Database Query Languages
 In Proc. 2nd Conference on Theoretical Aspects of Computer Software (TACS
, 1994
"... . The declarative programming paradigms used in constraint languages can lead to powerful extensions of Codd's relational data model. The development of constraint database query languages from logical database query languages has many similarities with the development of constraint logic progr ..."
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Cited by 62 (3 self)
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. The declarative programming paradigms used in constraint languages can lead to powerful extensions of Codd's relational data model. The development of constraint database query languages from logical database query languages has many similarities with the development of constraint logic programming from logic programming, but with the additional requirements of data efficient, setatatime, and bottomup evaluation. In this overview of constraint query languages (CQLs) we first present the framework of [41]. The principal idea is that: "the ktuple (or record) data type can be generalized by a conjunction of quantifierfree constraints over k variables". The generalization must preserve various language properties of the relational data model, e.g., the calculus/algebra equivalence, and have time complexity polynomial in the size of the data. We next present an algebra for dense order constraints that is simpler to evaluate than the calculus described in [41], and we sharpen some of...
Finitely Representable Databases
, 1995
"... : We study classes of infinite but finitely representable databases based on constraints, motivated by new database applications such as geographical databases. We formally define these notions and introduce the concept of query which generalizes queries over classical relational databases. We prove ..."
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Cited by 57 (8 self)
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: We study classes of infinite but finitely representable databases based on constraints, motivated by new database applications such as geographical databases. We formally define these notions and introduce the concept of query which generalizes queries over classical relational databases. We prove that in this context the basic properties of queries (satisfiability, containment, equivalence, etc.) are nonrecursive. We investigate the theory of finitely representable models and prove that it differs strongly from both classical model theory and finite model theory. In particular, we show that most of the well known theorems of either one fail (compactness, completeness, locality, 0/1 laws, etc.). An immediate consequence is the lack of tools to consider the definability of queries in the relational calculus over finitely representable databases. We illustrate this very challenging problem through some classical examples. We then mainly concentrate on dense order databases, and exhibit...
Query Languages for Bags and Aggregate Functions
 Journal of Computer and System Sciences
, 1997
"... Theoretical foundations for querying databases based on bags are studied in this paper. We fully determine the strength of many polynomialtime bag operators relative to an ambient query language. Then we obtain BQL, a query language for bags, by picking the strongest combination of these operators. ..."
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Cited by 57 (32 self)
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Theoretical foundations for querying databases based on bags are studied in this paper. We fully determine the strength of many polynomialtime bag operators relative to an ambient query language. Then we obtain BQL, a query language for bags, by picking the strongest combination of these operators. The relationship between the nested relational algebra and various fragments of BQL is investigated. The precise amount of extra power that BQL possesses over the nested relational algebra is determined. It is shown that the additional expressiveness of BQL amounts to adding aggregate functions to a relational language. The expressive power of BQL and related languages is investigated in depth. We prove that these languages possess the conservative extension property. That is, the expressibility of queries in these languages is independent of the nesting height of intermediate data. Using this result, we show that recursive queries, such as transitive closure, are not definable in BQL. A ne...
A Query Language Based on the Ambient Logic
, 2001
"... The ambient logic is a modal logic proposed to describe the structural and computational properties of distributed and mobile computation. The structural part of the ambient logic is, essentially, a logic of labeled trees, hence it turns out to be a good foundation for query languages for semistruct ..."
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Cited by 53 (10 self)
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The ambient logic is a modal logic proposed to describe the structural and computational properties of distributed and mobile computation. The structural part of the ambient logic is, essentially, a logic of labeled trees, hence it turns out to be a good foundation for query languages for semistructured data, much in the same way as first order logic is a fitting foundation for relational query languages. We define here a query language for semistructured data that is based on the ambient logic, and we outline an execution model for this language. The language turns out to be quite expressive. Its strong foundations and the equivalences that hold in the ambient logic are helpful in the definition of the language semantics and execution model.
An Experimental CLP Platform for Integrity Constraints and Abduction
 In Proceedings of FQAS2000, Flexible Query Answering Systems: Advances in Soft Computing series
, 2000
"... Integrity constraint and abduction are important in queryanswering systems for enhanced query processing and for expressing knowledge in databases. A straightforward characterization of the two is given in a subset of the language CHR _ , originally intended for writing constraint solvers to be a ..."
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Cited by 39 (18 self)
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Integrity constraint and abduction are important in queryanswering systems for enhanced query processing and for expressing knowledge in databases. A straightforward characterization of the two is given in a subset of the language CHR _ , originally intended for writing constraint solvers to be applied for CLP languages. This subset has a strikingly simple computational model that can be executed using existing, Prologbased technology. Together with earlier results, this confirms CHR _ as a multiparadigm platform for experimenting with combinations of topdown and bottomup evaluation, disjunctive databases and, as shown here, integrity constraint and abduction 1 Introduction Constraint logic programming (CLP) [10] is established as an extension to logic programming that adds higher expressibility and in some cases more efficient query evaluation. CLP has also given rise to a field of constraint databases [14]. In the present paper, we suggest CLP techniques applied for defini...
Semantic Representations And Query Languages For OrSets
 IN PROCEEDINGS OF 12TH ACM SYMPOSIUM ON PRINCIPLES OF DATABASE SYSTEMS
, 1993
"... Orsets were introduced by Imielinski, Naqvi and Vadaparty for dealing with limited forms of disjunctive information in database queries. Independently, Rounds used a similar notion for representing disjunctive and conjunctive information in the context of situation theory. In this paper we formulat ..."
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Cited by 36 (16 self)
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Orsets were introduced by Imielinski, Naqvi and Vadaparty for dealing with limited forms of disjunctive information in database queries. Independently, Rounds used a similar notion for representing disjunctive and conjunctive information in the context of situation theory. In this paper we formulate a query language with adequate expressive power for orsets. Using the notion of normalization of orsets, queries at the "structural" and "conceptual" levels are distinguished. Losslessness of normalization is established for a large class of queries. We have obtained upper bounds for the cost of normalization. An approach related to that of Rounds is used to provide semantics for orsets. We also treat orsets in the context of partial information in databases.