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86
Compositional Model Checking
, 1999
"... We describe a method for reducing the complexity of temporal logic model checking in systems composed of many parallel processes. The goal is to check properties of the components of a system and then deduce global properties from these local properties. The main difficulty with this type of approac ..."
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Cited by 3229 (69 self)
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We describe a method for reducing the complexity of temporal logic model checking in systems composed of many parallel processes. The goal is to check properties of the components of a system and then deduce global properties from these local properties. The main difficulty with this type of approach is that local properties are often not preserved at the global level. We present a general framework for using additional interface processes to model the environment for a component. These interface processes are typically much simpler than the full environment of the component. By composing a component with its interface processes and then checking properties of this composition, we can guarantee that these properties will be preserved at the global level. We give two example compositional systems based on the logic CTL*.
Relational Queries Computable in Polynomial Time
 Information and Control
, 1986
"... We characterize the polynomial time computable queries as those expressible in relational calculus plus a least fixed point operator and a total ordering on the universe. We also show that even without the ordering one application of fixed point suffices to express any query expressible with several ..."
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Cited by 324 (17 self)
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We characterize the polynomial time computable queries as those expressible in relational calculus plus a least fixed point operator and a total ordering on the universe. We also show that even without the ordering one application of fixed point suffices to express any query expressible with several alternations of fixed point and negation. This proves that the fixed point query hierarchy suggested by Chandra and Harel collapses at the first fixed point level. It is also a general result showing that in finite model theory one application of fixed point suffices. Introduction and Summary Query languages for relational databases have received considerable attention. In 1972 Codd showed that two natural languages for queries  one algebraic and the other a version of first order predicate calculus  have identical powers of expressibility, [Cod72]. Query languages which are as expressive as Codd's Relational Calculus are sometimes called complete. This term is misleading however becau...
Principles of Programming with Complex Objects and Collection Types
 Theoretical Computer Science
, 1995
"... We present a new principle for the development of database query languages that the primitive operations should be organized around types. Viewing a relational database as consisting of sets of records, this principle dictates that we should investigate separately operations for records and sets. Th ..."
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Cited by 151 (30 self)
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We present a new principle for the development of database query languages that the primitive operations should be organized around types. Viewing a relational database as consisting of sets of records, this principle dictates that we should investigate separately operations for records and sets. There are two immediate advantages of this approach, which is partly inspired by basic ideas from category theory. First, it provides a language for structures in which record and set types may be freely combined: nested relations or complex objects. Second, the fundamental operations for sets are closely related to those for other "collection types" such as bags or lists, and this suggests how database languages may be uniformly extended to these new types. The most general operation on sets, that of structural recursion, is one in which not all programs are welldefined. In looking for limited forms of this operation that always give rise to welldefined operations, we find a number of close ...
MinimalChange Integrity Maintenance Using Tuple Deletions
, 2008
"... We address the problem of minimalchange integrity maintenance in the context of integrity constraints in relational databases. We assume that integrityrestoration actions are limited to tuple deletions. We identify two basic computational issues: repair checking (is a database instance a repair of ..."
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Cited by 127 (10 self)
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We address the problem of minimalchange integrity maintenance in the context of integrity constraints in relational databases. We assume that integrityrestoration actions are limited to tuple deletions. We identify two basic computational issues: repair checking (is a database instance a repair of a given database?) and consistent query answers [ABC99] (is a tuple an answer to a given query in every repair of a given database?). We study the computational complexity of both problems, delineating the boundary between the tractable and the intractable. We consider denial constraints, general functional and inclusion dependencies, as well as key and foreign key constraints. Our results shed light on the computational feasibility of minimalchange integrity maintenance. The tractable cases should lead to practical implementations. The intractability results highlight the inherent limitations of any integrity enforcement mechanism, e.g., triggers or referential constraint actions, as a way of performing minimalchange integrity maintenance.
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 ..."
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Cited by 115 (11 self)
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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...
The complexity of relational query languages (extended abstract
 In Proceedings of the fourteenth annual ACM symposium on Theory of computing (STOC ’82
, 1982
"... Two complexity measures for query languages are proposed. Data complexity is the complexity of evaluating a query in the language as a function of the size of the database, and expression complexity is the complexity of ewduating a query in the language as a function of the size of the expression de ..."
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Cited by 111 (0 self)
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Two complexity measures for query languages are proposed. Data complexity is the complexity of evaluating a query in the language as a function of the size of the database, and expression complexity is the complexity of ewduating a query in the language as a function of the size of the expression defining the query. We study the data and expression complexity of logical langnages relational calculus and its extensions by transitive closure, fixpoint and second order existential quantification and algebraic languages relational algebra and its extensions by bounded and unbounded looping. The pattern which will bc shown is that the expression complexity of the investigated languages is one exponential higher then their data complexity, and for both types of complexity we show completeness in some complexity class. Research supported by a Weizrnann Postdoctoral Fellowship,
QBD*: a Graphical Query Language with Recursion
, 1990
"... One of the main problems in the database area is to define query languages characterized by both high expressive power and ease of use. In this paper, we propose a system to query databases, using diagrams as a standard user interface. The system, called Query by Diagram* (QBD*), makes use of a conc ..."
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Cited by 90 (16 self)
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One of the main problems in the database area is to define query languages characterized by both high expressive power and ease of use. In this paper, we propose a system to query databases, using diagrams as a standard user interface. The system, called Query by Diagram* (QBD*), makes use of a conceptual data model, a query language on this model and a graphical user interface. The conceptual model is the EntityRelationship Model; the query language, whose expressive power allows recursive queries, supports visual interaction. The main characteristics of the interface are the ease of use, and the availability of a rich set of primitives for schema selection and query formulation. Furthermore, we compare the expressive power of QBD* and G+, which are the only languages allowing recursive queries to be expressed graphically.
Toward Logic Tailored for Computational Complexity
 COMPUTATION AND PROOF THEORY
, 1984
"... Whereas firstorder logic was developed to confront the infinite it is often used in computer science in such a way that infinite models are meaningless. We discuss the firstorder theory of finite structures and alternatives to firstorder logic, especially polynomial time logic. ..."
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Cited by 87 (7 self)
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Whereas firstorder logic was developed to confront the infinite it is often used in computer science in such a way that infinite models are meaningless. We discuss the firstorder theory of finite structures and alternatives to firstorder logic, especially polynomial time logic.
On the equivalence of recursive and nonrecursive Datalog programs
 In Proc. of the 11th ACM SIGACT SIGMOD SIGART Symp. on Principles of Database Systems (PODS’92
, 1992
"... vardi Abstract: We study the problem of determining whether a given recursive Datalog program is equivalent to a given nonrecursive Datalog program. Since nonrecursive Datalog programs are equivalent to unions of conjunctive queries, we study also the problem of determining whether a given recursiv ..."
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Cited by 85 (5 self)
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vardi Abstract: We study the problem of determining whether a given recursive Datalog program is equivalent to a given nonrecursive Datalog program. Since nonrecursive Datalog programs are equivalent to unions of conjunctive queries, we study also the problem of determining whether a given recursive Datalog program is contained in a union of conjunctive queries. For this problem, we prove doubly exponential upper and lower time bounds. For the equivalence problem, we prove triply exponential upper and lower time bounds. 1
Relational Expressive Power of Constraint Query Languages
 Journal of the ACM
, 1995
"... The expressive power of firstorder query languages with several classes of equality and inequality constraints is studied in this paper. We settle the conjecture that recursive queries such as parity test and transitive closure cannot be expressed in the relational calculus augmented with polynomia ..."
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Cited by 83 (18 self)
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The expressive power of firstorder query languages with several classes of equality and inequality constraints is studied in this paper. We settle the conjecture that recursive queries such as parity test and transitive closure cannot be expressed in the relational calculus augmented with polynomial inequality constraints over the reals. Furthermore, noting that relational queries exhibit several forms of genericity, we establish a number of collapse results of the following form: The class of generic boolean queries expressible in the relational calculus augmented with a given class of constraints coincides with the class of queries expressible in the relational calculus (with or without an order relation). We prove such results for both the natural and activedomain semantics. As a consequence, the relational calculus augmented with polynomial inequalities expresses the same classes of generic boolean queries under both the natural and activedomain semantics. In the course of proving...