C. Baral and J. Lobo. Formal Characterization of Active Databases. In D. Pedreschi and C. Zaniolo, editors, Workshop of Logic on Databases (LID '96), volume 1154 of Lecture Notes in Computer Science, pages 175--195, San Miniato, Italy, 1996.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....of an Action Base, Action Constraint, and Action Program, and discuss how they work together. 3.1 Action Base In this section, we will introduce the concept of an action and describe how the effects of actions are implemented. In most work in AI [73, 41, 82] and logical approaches to action [12], it is assumed that states are sets of ground logical atoms. In the fertile area of active databases, it is assumed that states reflect the content of a relational database. However, neither of these two approaches is adequate for our purpose because the state of an agent which uses the software ....

C. Baral and J. Lobo. Formal Characterization of Active Databases. In D. Pedreschi and C. Zaniolo, editors, Workshop of Logic on Databases (LID '96), volume 1154 of Lecture Notes in Computer Science, pages 175--195, San Miniato, Italy, 1996.

....has been analyzed in (Picouet and Vianu, 1995) where computations over time are considered. If we consider evaluation of action programs over time, then over a fixed active domain, all computations in PSPACE are feasible, while if new values can be suitably created, all computations are possible. (Baral and Lobo, 1996) use situation semantics (a more general version of Datalog 1S) to give a logic program semantics for active rules. Gottlob et al. 1996) proposed a semantics for active rules which allowed the user to specify different conflict resolution policies. Lud ascher et al. 1997) develop methods to ....

Baral, C. and Lobo, J. (1996). Formal Characterization of Active Databases. In Pedreschi, D. and Zaniolo, C., editors, Workshop of Logic on Databases (LID '96), volume 1154 of Lecture Notes in Computer Science, pages 175--195, San Miniato, Italy.

....similar in spirit to the work in active databases (ADBs) where the dynamics of a database is specified through event condition action (ECA) rules triggered by events. However, ADBs have in general no declarative semantics, and only one rule at a time fires, possibly causing successive events. In [Baral and Lobo, 1996] , a declarative characterization of ADBs is given, in terms of a reduction to logic programs, by using situation calculus notation. Our language for update policies is also related to action languages, which can be compiled to logic programs as well (cf. e.g. Lifschitz and Turner, 1999] A ....

C. Baral and J. Lobo. Formal characterization of active databases. In Proc. LID'96, LNCS 1154, pp. 175-195. Springer, 1996.

....properties in some specific execution model, a lot of research aims at formalizing and characterizing the semantics of active rules in the first place. Once a formal model has been established, abstract properties like termination or expressiveness can be studied. Situation Calculus Based. In [BL96,BLT97] a language L active for active rules is developed, which allows to formalize and reason about the behavior of active rules. The language borrows from L 1 [BGP97] an extension of the action description language A [GL93] used for modeling actual and hypothetical actions and situations, ....

C. Baral and J. Lobo. Formal Characterization of Active Databases. In Pedreschi and Zaniolo [PZ96], pp. 175--195. 34

....the previous state in that it no longer satisfies the code call atoms in the delete list, but satisfies the atoms in the add list. This is also the notion of action used in works on reasoning with actions by Baral (Baral and Gelfond 1993; Baral, Gelfond, and Provetti 1995; Baral and Gelfond 1994; Baral and Lobo 1996), Baldoni (Baldoni, Giordano, Martelli, and Patti 1998) and Gelfond and Lifschitz (Gelfond and Lifschitz 1993; Gelfond and Lifschitz 1998; Lifschitz 1997) We would like to extend this general definition, to allow an action to have a duration or temporal extent. For example, consider the heli ....

Baral, C. and J. Lobo (1996). Formal Characterization of Active Databases.

....of an Action Base, Action Constraint, and Action Program, and discuss how they work together. 3.1 Action Base In this section, we will introduce the concept of an action and describe how the effects of actions are implemented. In most work in AI [73, 41, 82] and logical approaches to action [12], it is assumed that states are sets of ground logical atoms. In the fertile area of active databases, it is assumed that states reflect the content of a relational database. However, neither of these two approaches is adequate for our purpose because the state of an agent which uses the software ....

C. Baral and J. Lobo. Formal Characterization of Active Databases. In D. Pedreschi and C. Zaniolo, editors, Workshop of Logic on Databases (LID '96), volume 1154 of Lecture Notes in Computer Science, pages 175-- 195, San Miniato, Italy, 1996.

....of an Action Base, Action Constraint, and Action Program, and discuss how they work together. 4.1 Action Base In this section, we will introduce the concept of an action and describe how the effects of actions are implemented. In most work in AI [82, 44, 90] and logical approaches to action [11], it is assumed that states are sets of ground logical atoms. In the fertile area of active databases, it is assumed that states reflect the content of a relational database. However, neither of these two approaches is adequate for our purpose because the state of an agent which uses the software ....

C. Baral and J. Lobo. Formal Characterization of Active Databases. In: Proc. Workshop of Logic on Databases (LID '96), D. Pedreschi and C. Zaniolo (eds), San Miniato, Italy, LNCS 1154, 1996.

....trigger action A. Zaniolo has noted the need for a declarative semantics of triggers ( Zaniolo, 1993] and [Zaniolo, 1996] He has developed a unified semantics for active and deductive databases, and has shown how active database rules relate to transaction conscious stable model semantics. In [Baral and Lobo, 1996], a first step is proposed towards characterizing active databases. ffl Data mining and inductive inference involve discovering generalizations that hold over a database (or a logic program) Such generalizations may be considered as integrity constraints that must be true with respect to the ....

Baral, C. and Lobo, J. (1996). Formal characterization of active databases. In Logic in Databases (LID'96), San Miniato, Italy. Springer.

....language to allow additional constructs such as natural events, explicit time, continuous actions, and various kinds of action occurrences beyond the simple ones that we have such as non preventable occurrences, conditional occurrences, eventual occurrences, and triggered occurrences. One of us [9] has already participated in extending L to allow triggers so as to formulate active databases; but this high level formulation has not been axiomatized using circumscription. Introduce the notion of current situation and planning from the current situation to Pinto and Reiter s ....

C. Baral, J. Lobo, Formal characterization of active databases, in: Proc. International Workshop on Logic in Databases, 1996.

.... in the spirit of the action description language A [26] the description of the language is based on AK in [11] L active in [7] and ADC in [6] Action theories have been successfully used in reasoning about robot control programs [37] and in the logical formalization of active databases [5, 7] (reasoning about parameterized actions, qualification and ramification constraints, concurrent execution of actions [29] The later use makes it more appropriate than the traditional approach of program correctness [23] which has been designed for standard programming languages and lacks the ....

C. Baral and J. Lobo. Formal characterization of active databases. In International Workshop on Logic in Databases (LID'96), 1996.

....from the basic insert, delete and update actions to SQL update statements. In this paper by an action we will usually refer to an uninterruptable transaction. To specify the effects of an action on a database we borrow constructs from the specification language A [GL93] and our earlier work in [BL96, BLT97]. In the following by a fluent we will mean a database fact, and by a fluent literal we will mean either a database fact or its negation. Effects of actions are specified through effect axioms of the following form: a(X) causes f(Y ) if p 1 (X 1 ) pn (Xn ) 2.1) where a(X) is an action ....

C. Baral and J. Lobo. Formal characterization of active databases. In Proc. of International Workshop on Logic in Databases -- LID'96 (LNCS 1154), pages 175--195, 1996.

....extend our language to allow additional constructs such as natural events, continuous actions, and various kinds of action occurrences beyond the simple ones that we have such as non preventable occurrences, conditional occurrences, eventual occurrences, and triggers occurrences. One of us [BarLob96] has already participated in extending L to allow triggers so as to formulate active databases; but this high level formulation has not been axiomatized using circumscription. Introduce the notion of current situation and planning from the current situation to Pinto and Reiter s ....

Baral, C. and Lobo, J. 1996. Formal Characterization of Active Databases. In Proc. of International Workshop on Logic in Databases.

....to allow additional constructs such as natural events, explicit time, continuous actions, and various kinds of action occurrences beyond the simple ones that we have such as non preventable occurrences, conditional occurrences, eventual occurrences, and triggered occurrences. One of us [BarLob96] has already participated in extending L to allow triggers so as to formulate active databases; but this high level formulation has not been axiomatized using circumscription. introduce the notion of current situation and planning from the current situation to Pinto and Reiter s ....

Baral, C. and Lobo, J. 1996. Formal Characterization of Active Databases. In Proc. of International Workshop on Logic in Databases.

....Apply above returns failure return fail. Let DBn i 1 = S i;1 ; S i;p i ]DBn i . end i : i 1 end 5. return DB;DB 1 ; DBn ffi SeqA0 ffi : ffi SeqAq 4. 3 Declarative Semantics Due to lack of space we will not be presenting an independent declarative semantics in the style of [4] or [27] We will use the following working definition. We say DB 0 ; DBm is a sequence of states that the state DB 0 goes through (or DB 0 ; DBm is the evolution of DB 0 ) when applied with a sequence of SQL modification statement S 1 ; S r , in presence of triggers ....

C. Baral and J. Lobo. Formal characterization of active databases. In Proc. of International Workshop on Logic in Databases, 1996.

....making a clear distinction between actual and hypothetical execution of the actions, one can make claims and about the (possible) effects of an actions sequence and prove them, without actually executing it. The results that we present extend the active database description language introduced in [5] with additional semantic dimensions. We demonstrate through examples how we can encode the active rules and their operational behavior from different existing systems. 1 Introduction and Motivation The core concept which makes a database system active is the concept of an active rule. The origin ....

....system active and the existing systems have taken different choices among appropriate alternatives. This has resulted in recognizing [14, 30, 40] that there has been very little activity on formal foundations of active behavior. Some recent results on formal characterization of active database are [16, 18, 17, 5, 31, 37, 41, 42]. This paper extends the language L active introduced in [5] to describe the semantics of active database systems. L active is based on the action description language L 0 of Baral, Gelfond and Provetti [4] One of the advantages of L 0 is the clear distinction the language makes between actual ....

[Article contains additional citation context not shown here]

C. Baral and J. Lobo. Formal characterization of active databases. In International Workshop on Logic in Databases, 1996.

....making a clear distinction between actual and hypothetical execution of the actions, one can make claims and about the (possible) effects of an actions sequence and prove them, without actually executing it. The results that we present extend the active database description language introduced in [5] with additional semantic dimensions. We demonstrate through examples how we can encode the active rules and their operational behavior from different existing systems. 1 Introduction and Motivation The core concept which makes a database system active is the concept of an active rule. The origin ....

....system active and the existing systems have taken different choices among appropriate alternatives. This has resulted in recognizing [14, 30, 40] that there has been very little activity on formal foundations of active behavior. Some recent results on formal characterization of active database are [16, 18, 17, 5, 31, 37, 41, 42]. This paper extends the language L active introduced in [5] to describe the semantics of active database systems. L active is based on the action description language L 0 of Baral, Gelfond and Provetti [4] One of the advantages of L 0 is the clear distinction the language makes between actual ....

[Article contains additional citation context not shown here]

C. Baral and J. Lobo. Formal characterization of active databases. In International Workshop on Logic in Databases, 1996.

.... spirit of the action description language A [GL93] Our approach of using action theories is motivated by its success in reasoning about robot control programs [LRL 97] and also by its use in the logical formalization of database updates [Rei94] transactions [BK93] and active databases [BL96] The later use makes it more appropriate than the traditional approach of program correctness [Cou90] which has been designed for standard programming languages and lacks the flexibility of defining new operators (in our case, operations are called activities. We can also avoid the use of full ....

C. Baral and J. Lobo. Formal characterization of active databases. In Proc. of International Workshop on Logic in Databases, 1996.

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