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37
Towards Tractable Algebras for Bags
, 1993
"... Bags, i.e. sets with duplicates, are often used to implement relations in database systems. In this paper, we study the expressive power of algebras for manipulating bags. The algebra we present is a simple extension of the nested relation algebra. Our aim is to investigate how the use of bags in ..."
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Cited by 56 (5 self)
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Bags, i.e. sets with duplicates, are often used to implement relations in database systems. In this paper, we study the expressive power of algebras for manipulating bags. The algebra we present is a simple extension of the nested relation algebra. Our aim is to investigate how the use of bags
Tractable Iteration Mechanisms for Bag Languages
, 1997
"... The goal of this paper is to study tractable iteration mechanisms for bags. The presence of duplicates in bags prevents iteration mechanisms developed in the context of sets to be directly applied to bags without losing tractability. We study two constructs for controlling tractability of iteration ..."
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Cited by 2 (0 self)
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The goal of this paper is to study tractable iteration mechanisms for bags. The presence of duplicates in bags prevents iteration mechanisms developed in the context of sets to be directly applied to bags without losing tractability. We study two constructs for controlling tractability of iteration
Towards a complete classification of tractability in allen's algebra
 Proceedings of the 15th International Joint Conference on Artificial Intelligence (IJCAI '97
, 1997
"... We characterise the set of subalgebras of Allen's algebra which have a tractable satisfiability problem, and in addition contain certain basic relations. The conclusion is that no tractable subalgebra that is not known in the literature can contain more than the three basic relations This means ..."
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Cited by 9 (6 self)
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We characterise the set of subalgebras of Allen's algebra which have a tractable satisfiability problem, and in addition contain certain basic relations. The conclusion is that no tractable subalgebra that is not known in the literature can contain more than the three basic relations
Towards a Complete Classification of Tractability in Point Algebras for Nonlinear Time
 In Proceedings of the 5th International Conference on Principles and Practice of Constraint Programming (CP99
, 1999
"... . Efficient reasoning about temporal constraints over nonlinear time models is vital in numerous application areas, such as planning, distributed systems and cooperating agents. We identify all tractable subclasses of the point algebra for partiallyordered time and examine one large, nontrivial ..."
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Cited by 8 (3 self)
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. Efficient reasoning about temporal constraints over nonlinear time models is vital in numerous application areas, such as planning, distributed systems and cooperating agents. We identify all tractable subclasses of the point algebra for partiallyordered time and examine one large
Towards compact and tractable automatonbased representations of time granularity
 In Proceedings of the 8th Italian Conference on Theoretical Computer Science (ICTCS), volume 2841 of LNCS
, 2003
"... Abstract. Different approaches to time granularity have been proposed in the database literature to formalize the notion of calendar, based on algebraic, logical, and stringbased formalisms. In this paper, we further develop an alternative approach based on automata, originally proposed in [4], whi ..."
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Cited by 8 (2 self)
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Abstract. Different approaches to time granularity have been proposed in the database literature to formalize the notion of calendar, based on algebraic, logical, and stringbased formalisms. In this paper, we further develop an alternative approach based on automata, originally proposed in [4
Islands of tractability for relational constraints: towards dichotomy results for the description logic EL
"... EL is a tractable description logic serving as the logical underpinning of largescale ontologies. We launch a
systematic investigation of the boundary between tractable and intractable reasoning in EL under relational
constraints. E.g., we show that there are (modulo equivalence) exactly 3 universa ..."
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Cited by 5 (2 self)
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universal constraints on a transitive
and re#29;exive relation under which reasoning is tractable: being a singleton set, an equivalence relation, or
the empty constraint. We prove a number of results of this type and discuss a spectrum of open problems
including generalisations to the algebraic semantics
Nonlinear Loop Invariant Generation using Gröbner Bases
, 2004
"... We present a new technique for the generation of nonlinear (algebraic) invariants of a program. Our technique uses the theory of ideals over polynomial rings to reduce the nonlinear invariant generation problem to a numerical constraint solving problem. So far, the literature on invariant generati ..."
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Cited by 60 (4 self)
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of constraints, such that all the solutions to these constraints correspond to nonlinear (algebraic) loop invariants of the program. We discuss some tradeoffs between the completeness of the technique and the tractability of the constraintsolving problem generated. The application of the technique
Toward InteractionOriented Programming
, 1996
"... Although much progress has been made in agent theory and practice, bottlenecks remain in the construction of complex multiagent systems. We introduce interactionoriented programming (IOP) as an approach to orchestrate the interactions among agents. IOP is more tractable and practical than general a ..."
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Cited by 6 (0 self)
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Although much progress has been made in agent theory and practice, bottlenecks remain in the construction of complex multiagent systems. We introduce interactionoriented programming (IOP) as an approach to orchestrate the interactions among agents. IOP is more tractable and practical than general
Towards a Theory of Bulk Types
, 1991
"... A database programming language can model application domains most naturally if it supports several bulk types, e.g., lists, sets, and relations. Indeed some persistent programming languages permit the programmer to define new bulk types that are appropriate to the application domain. Such a richly ..."
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Cited by 8 (1 self)
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types. The theory is based on four operations  three constructor operations and one iterator  that obey certain algebraic laws. In addition, a rich set of additional operations can be defined in terms of the basic operations. Sets, bags, lists, certain trees, relations, and finite mappings are all
Elements of a Relational Theory of Datatypes
 Formal Program Development, volume 755 of Lecture Notes in Computer Science
, 1993
"... The "Boom hierarchy" is a hierarchy of types that begins at the level of trees and includes lists, bags and sets. This hierarchy forms the basis for the calculus of total functions developed by Bird and Meertens, and which has become known as the "BirdMeertens formalism". This p ..."
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Cited by 43 (0 self)
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. The algebra is an algebra of datatypes oriented towards the calculation of polymorphic functions and relations. Its design d...
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