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Computational LambdaCalculus and Monads
, 1988
"... The calculus is considered an useful mathematical tool in the study of programming languages, since programs can be identified with terms. However, if one goes further and uses fijconversion to prove equivalence of programs, then a gross simplification 1 is introduced, that may jeopardise the ..."
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Cited by 505 (7 self)
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The calculus is considered an useful mathematical tool in the study of programming languages, since programs can be identified with terms. However, if one goes further and uses fijconversion to prove equivalence of programs, then a gross simplification 1 is introduced, that may jeopardise the applicability of theoretical results to real situations. In this paper we introduce a new calculus based on a categorical semantics for computations. This calculus provides a correct basis for proving equivalence of programs, independent from any specific computational model. 1 Introduction This paper is about logics for reasoning about programs, in particular for proving equivalence of programs. Following a consolidated tradition in theoretical computer science we identify programs with the closed terms, possibly containing extra constants, corresponding to some features of the programming language under consideration. There are three approaches to proving equivalence of programs: ffl T...
Constraint Query Languages
, 1992
"... We investigate the relationship between programming with constraints and database query languages. We show that efficient, declarative database programming can be combined with efficient constraint solving. The key intuition is that the generalization of a ground fact, or tuple, is a conjunction ..."
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Cited by 380 (44 self)
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We investigate the relationship between programming with constraints and database query languages. We show that efficient, declarative database programming can be combined with efficient constraint solving. The key intuition is that the generalization of a ground fact, or tuple, is a conjunction of constraints over a small number of variables. We describe the basic Constraint Query Language design principles and illustrate them with four classes of constraints: real polynomial inequalities, dense linear order inequalities, equalities over an infinite domain, and boolean equalities. For the analysis, we use quantifier elimination techniques from logic and the concept of data complexity from database theory. This framework is applicable to managing spatial data and can be combined with existing multidimensional searching algorithms and data structures.
Answering Recursive Queries Using Views
 In PODS
, 1997
"... We consider the problem of answering datalog queries using materialized views. The ability to answer queries using views is crucial in the context of information integration. Previous work on answering queries using views restricted queries to being conjunctive. We extend this work to general recurs ..."
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Cited by 208 (9 self)
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recursive queries: Given a datalog program P and a set of views, is it possible to find a datalog program that is equivalent to P and only uses views as EDB predicates? In this paper, we show that the problem of whether a datalog program can be rewritten into an equivalent program that only uses views
Complexity of answering queries using materialized views
 In Proceedings of the Seventeenth ACM Symposium on Principles of Database Systems, PODS ’98
, 1998
"... WC study the complexity of the problem of answering queries using materinlized views, This problem has attracted a lot of attention recently because of its relevance in data integration. Previous work considered only conjunctive view definitions. We examine the consequences of allowing more expres ..."
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Cited by 315 (5 self)
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WC study the complexity of the problem of answering queries using materinlized views, This problem has attracted a lot of attention recently because of its relevance in data integration. Previous work considered only conjunctive view definitions. We examine the consequences of allowing more expressive view definition languages. Tl~olanguagcsweconsiderforviewdefinitionsanduserqueriesare: conjunctive qucrics with inequality, positive queries, datalog, and firstorder logic. We show that the complexity of the problem depcnds on whether views are assumed to store all the tuples that satisfy the view definition, or only a subset of it. Finally, we apply the results to the view consistency and view selfmaintainability problems which nrise in data warehousing. 1
Stable models and an alternative logic programming paradigm
 In The Logic Programming Paradigm: a 25Year Perspective
, 1999
"... In this paper we reexamine the place and role of stable model semantics in logic programming and contrast it with a least Herbrand model approach to Horn programs. We demonstrate that inherent features of stable model semantics naturally lead to a logic programming system that offers an interesting ..."
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Cited by 308 (20 self)
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In this paper we reexamine the place and role of stable model semantics in logic programming and contrast it with a least Herbrand model approach to Horn programs. We demonstrate that inherent features of stable model semantics naturally lead to a logic programming system that offers an interesting alternative to more traditional logic programming styles of Horn logic programming, stratified logic programming and logic programming with wellfounded semantics. The proposed approach is based on the interpretation of program clauses as constraints. In this setting programs do not describe a single intended model, but a family of stable models. These stable models encode solutions to the constraint satisfaction problem described by the program. Our approach imposes restrictions on the syntax of logic programs. In particular, function symbols are eliminated from the language. We argue that the resulting logic programming system is wellattuned to problems in the class NP, has a welldefined domain of applications, and an emerging methodology of programming. We point out that what makes the whole approach viable is recent progress in implementations of algorithms to compute stable models of propositional logic programs. 1
Equivalence, QueryReachability, and Satisfiability in Datalog Extensions (Extended Abstract)
 In Proceedings of the ACM Symposium on Principles of Database Systems
, 1993
"... Alon Y. Levy Stanford University levy@cs.stanford.edu Inderpal Singh Mumick AT&T Bell Laboratories mumick@research.att.com Yehoshua Sagiv y Hebrew University sagiv@cs.huji.ac.il Oded Shmueli z TechnionIsrael Institute of Technology oshmu@cs.technion.ac.il Abstract We consider the ..."
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Cited by 17 (8 self)
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that negation is applied only to EDB predicates or that all EDB predicates are unary. In the latter case, we show that equivalence is also decidable. The algorithms we present are also used to push constraints from a given query to the EDB predicates. Finally, we show that satisfiability is undecidable
Constraints and Redundancy in Datalog
 IN PROCEEDINGS OF THE ELEVENTH SYMPOSIUM ON PRINCIPLES OF DATABASE SYSTEMS (PODS
, 1992
"... Two types of redundancies in datalog programs are considered. Redundancy based on reachability eliminates rules and predicates that do not participate in any derivation tree of a fact for the query predicate. Redundancy based on irrelevance is similar, but considers only minimal derivation trees, ..."
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Cited by 34 (15 self)
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push constraints from the given query and rules to the EDB predicates. Under certain assumptions discussed in the paper, the constraints are pushed to the EDB as tightly as possible.
EDB: Knowledge Technologies for Ancient Greek and Latin Epigraphy
"... Abstract. Classical Greek and Latin culture is the very foundation of the identity of modern Europe. Today, a variety of modern subjects and disciplines have their roots in the classical world: from philosophy to architecture, from geometry to law. However, only a small fraction of the total produc ..."
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. In this paper, we describe the system EDB (Epigraphic Database Bari) which stores about 30,000 Christian inscriptions of Rome, including those published in the Inscriptiones Christianae Vrbis Romae septimo saeculo antiquiores, nova series editions. EDB provides, in addition to the possibility of storing
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