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Datalog with Constraints: A Foundation for Trust Management Languages
 In PADL ’03: Proceedings of the 5th International Symposium on Practical Aspects of Declarative Languages
, 2003
"... Trust management (TM) is a promising approach for authorization and access control in distributed systems, based on signed distributed policy statements expressed in a policy language. Although several TM languages are semantically equivalent to subsets of Datalog, Datalog is not su#ciently expr ..."
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Cited by 121 (11 self)
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Trust management (TM) is a promising approach for authorization and access control in distributed systems, based on signed distributed policy statements expressed in a policy language. Although several TM languages are semantically equivalent to subsets of Datalog, Datalog is not su#ciently expressive for finegrained control of structured resources. We define the class of linearly decomposable unary constraint domains, prove that Datalog extended with constraints in any combination of such constraint domains is tractable, and show that permissions associated with structured resources fall into this class. We also present a concrete declarative TM language, RT 1 , based on constraint Datalog, and use constraint Datalog to analyze another TM system, KeyNote, which turns out to be less expressive than RT 1 in significant respects, yet less tractable in the worst case. Although constraint Datalog has been studied in the context of constraint databases, TM applications involve di#erent kinds of constraint domains and have different computational complexity requirements.
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 114 (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...
Multiple counters automata, safety analysis and Presburger arithmetic
, 1998
"... We consider automata with counters whose values are updated according to signals sent by the environment. A transition can be fired only if the values of the counters satisfy some guards (the guards of the transition). We consider guards of the form y i #y j +c i;j where y i is either x 0 i or ..."
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Cited by 111 (1 self)
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We consider automata with counters whose values are updated according to signals sent by the environment. A transition can be fired only if the values of the counters satisfy some guards (the guards of the transition). We consider guards of the form y i #y j +c i;j where y i is either x 0 i or x i , the values of the counter i respectively after and before the transition, and # is any relational symbol in f=; ; ; ?; !g. We show that the set of possible counter values which can be reached after any number of iterations of a loop is definable in the additive theory of N (or Z or R depending on the type of the counters). This result can be used for the safety analysis of multiple counters automata.
An Access Control Model Supporting Periodicity Constraints and Temporal Reasoning
 ACM Transactions on Database Systems
, 1998
"... this paper, we present an access control model in which periodic temporal intervals are associated with authorizations. An authorization is automatically granted in the specified intervals and revoked when such intervals expire. Deductive temporal rules with periodicity and order constraints are pro ..."
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Cited by 98 (17 self)
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this paper, we present an access control model in which periodic temporal intervals are associated with authorizations. An authorization is automatically granted in the specified intervals and revoked when such intervals expire. Deductive temporal rules with periodicity and order constraints are provided to derive new authorizations based on the presence or absence of other authorizations in specific periods of time. We provide a solution to the problem of ensuring the uniqueness of the global set of valid authorizations derivable at each instant, and we propose an algorithm to compute this set. Moreover, we address issues related to the efficiency of access control by adopting a materialization approach. The resulting model provides a high degree of flexibility and supports the specification of several protection requirements that cannot be expressed in traditional access control models.
Temporal Logic in Information Systems
 In Logics for Databases and Information Systems, Kluwer Academic Publishers
, 1998
"... ..."
The Complexity of Query Evaluation in Indefinite Temporal Constraint Databases
 Theoretical Computer Science
, 1997
"... In previous work we have developed the scheme of indefinite Lconstraint databases where L, the parameter, is a firstorder constraint language. This scheme extends the constraint database proposal of Kanellakis, Kuper and Revesz to include indefinite (or uncertain) information in the style of Imiel ..."
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Cited by 27 (11 self)
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In previous work we have developed the scheme of indefinite Lconstraint databases where L, the parameter, is a firstorder constraint language. This scheme extends the constraint database proposal of Kanellakis, Kuper and Revesz to include indefinite (or uncertain) information in the style of Imielinski and Lipski. In this paper we study the complexity of query evaluation in an important instance of this abstract scheme: indefinite temporal constraint databases. Our results indicate that the data/combined complexity of query evaluation does not change when we move from queries in relational calculus over relational databases, to queries in relational calculus with temporal constraints over temporal constraint databases. This fact remains true even when we consider query evaluation in relational databases with indefinite information vs. query evaluation in indefinite temporal constraint databases. In the course of our work, we provide precise bounds on the complexity of decision/quanti...
Constraint Databases: A Survey
 Semantics in Databases, number 1358 in LNCS
, 1998
"... . Constraint databases generalize relational databases by finitely representable infinite relations. This paper surveys the state of the art in constraint databases: known results, remaining open problems and current research directions. The paper also describes a new algebra for databases with inte ..."
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Cited by 25 (3 self)
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. Constraint databases generalize relational databases by finitely representable infinite relations. This paper surveys the state of the art in constraint databases: known results, remaining open problems and current research directions. The paper also describes a new algebra for databases with integer order constraints and a complexity analysis of evaluating queries in this algebra. In memory of Paris C. Kanellakis 1 Introduction There is a growing interest in recent years among database researchers in constraint databases, which are a generalization of relational databases by finitely representable infinite relations. Constraint databases are parametrized by the type of constraint domains and constraint used. The good news is that for many parameters constraint databases leave intact most of the fundamental assumptions of the relational database framework proposed by Codd. In particular, 1. Constraint databases can be queried by constraint query languages that (a) have a semantics ba...
A few graphbased relational numerical abstract domains
 Static Analysis: Proceedings of the 9th International Symposium
, 2002
"... Abstract. This article presents the systematic design of a class of relational numerical abstract domains from nonrelational ones. Constructed domains represent sets of invariants of the form (vj − vi ∈ C), where vj and vi are two variables, and C lives in an abstraction of P(Z), P(Q), or P(R). We ..."
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Cited by 23 (1 self)
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Abstract. This article presents the systematic design of a class of relational numerical abstract domains from nonrelational ones. Constructed domains represent sets of invariants of the form (vj − vi ∈ C), where vj and vi are two variables, and C lives in an abstraction of P(Z), P(Q), or P(R). We will call this family of domains weakly relational domains. The underlying concept allowing this construction is an extension of potential graphs and shortestpath closure algorithms in exoticlike algebras. Example constructions are given in order to retrieve wellknown domains Interpretation framework in order to design various static analyses. A major benefit of this construction is its modularity, allowing to quickly implement new abstract domains from existing ones. 1
Datalog queries of set constraint databases
 In Proceedings of the International Conference on Database Theory
, 1995
"... Abstract. Extension of the relational database model to represent complex data has been a focus of much research in recent years. At the same time, an alternative extension of the relational database model has proposed using constraint databases that finitely describe infinite relations. This paper ..."
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Cited by 21 (7 self)
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Abstract. Extension of the relational database model to represent complex data has been a focus of much research in recent years. At the same time, an alternative extension of the relational database model has proposed using constraint databases that finitely describe infinite relations. This paper attempts to combine these two divergent approaches. In particular a query language called Datalog with set order constraints, or Datalog ⊂ P(Z) , is proposed. This language can express many natural problems with sets, including reasoning about inheritance hierarchies. Datalog ⊂ P(Z) queries over set constraint databases are shown to be evaluable bottomup in closed form and to have DEXPTIMEcomplete data complexity. 1
Symbolic Userdefined Periodicity in Temporal Relational Databases
 IEEE Transactions on Knowledge and Data Engineering
, 2003
"... Abstract—Calendars and periodicity play a fundamental role in many applications. Recently, some commercial databases started to support userdefined periodicity in the queries in order to provide “a humanfriendly way of handling time ” (see, e.g., TimeSeries in Oracle 8). On the other hand, only fe ..."
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Cited by 19 (9 self)
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Abstract—Calendars and periodicity play a fundamental role in many applications. Recently, some commercial databases started to support userdefined periodicity in the queries in order to provide “a humanfriendly way of handling time ” (see, e.g., TimeSeries in Oracle 8). On the other hand, only few relational data models support userdefined periodicity in the data, mostly using “mathematical” expressions to represent periodicity. In this paper, we propose a highlevel “symbolic ” language for representing userdefined periodicity which seems to us more humanoriented than mathematical ones, and we use the domain of Gadia’s temporal elements in order to define its properties and its extensional semantics. We then propose a temporal relational model which supports userdefined “symbolic ” periodicity (e.g., to express “on the second Monday of each month”) in the validity time of tuples and also copes with frame times (e.g., “from 1/1/98 to 28/2/98”). We define the temporal counterpart of the standard operators of the relational algebra, and we introduce new temporal operators and functions. We also prove that our temporal algebra is a consistent extension of the classical (atemporal) one. Moreover, we define both a fully symbolic evaluation method for the operators on the periodicities in the validity times of tuples, which is correct but not complete, and semisymbolic one, which is correct and complete, and study their computational complexity. Index Terms—Temporal relational model and algebra, userdefined symbolic periodicity in the validity time, highlevel “symbolic” language, symbolic (intensional) evaluation method, semisymbolic evaluation method, userfriendly treatment of periodicity, integration and extension of artificial intelligence and temporal databases techniques. 1