R. Kowalski: "Database Updates in the Event Calculus", in Journal of Logic Programming, Vol. 12, June 1992, pp 121-146.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....by these events and maximal time periods during which these properties hold . Most subsequent developments of the EC used a simpli ed variant of the original EC based on time points instead of time periods. This simpli ed event calculus EC was applied to problems such as database updates [27], planning [14, 34] explanation and hypothetical reasoning [48, 41] modeling temporal databases [52] air trac management [51] and protocol speci cation [13] In this paper, we will use a slight variant of the Event Calculus as de ned in [50] In this event calculus, the ontological primitive ....

R.A. Kowalski. Database updates in the event calculus. Journal of Logic Programming, 1992.

....o if and only if it is known that e i occurs before e j . EC updates are of additive nature only and they just consist in the acquisition of new atomic events and relative information about properties initiated and terminated by them, and or of further ordering information about the given events [12]. Hence, update processing in EC reduces to the addition of such data, provided that they are consistent and non redundant with the current stored information. The set of MVIs for any given property p has been traditionally computed at query time according to a simple (and expensive) ....

....on the set of events E, which represents our current knowledge about the time ordering between events. EC updates consist in the acquisition of new atomic events and relative information about properties initiated and terminated by them, and or new ordering information about the given events [12]. Hence, update processing in EC reduces to the addition of such data, provided that they are consistent and nonredundant with respect to the already stored information. be a structure for EC and o be a knowledge state. The of EC is the set of property labeled pairs of events of the ....

R. Kowalski. Database updates in the event calculus. Journal of Logic Programming, 12:121--146, 1992.

....E is the set of events and, for every e i , e j there exists (e i , e j ) o if and only if it is known that e i occurs before e j . EC updates are of additive nature only and they just consist in the acquisition of new events and or of further ordering information about the given events [6]. Hence, update processing in EC reduces to the addition of such data, provided that they are consistent with the current binary acyclic relation o. The set of MVIs for any given property p has been traditionally computed at query time according to a simple (and expensive) generate and test ....

R. Kowalski. Database updates in the event calculus. Journal of Logic Programming, 12:121--146, 1992.

.... negation as failure is an unsolved issue in Logic Programming, which plays against the use of this approach in reasoning about actions and change [44] In order to simplify the Original Event Calculus several versions of it were proposed without using the notion of time interval in its ontology [20][29] 35] however these variations suffered from lack of generality, since they give incorrect results if the event information is incomplete. A new event calculus was proposed in [30] joining the generality of the original version to the simplicity of its extensions based in time points. ....

R. Kowalski. Database updates in event calculus. Journal of Logic Programming, 12(162):121--146, 1992.

.... each event we either specify its relative position with respect to some other events (e.g. event el occurs before event e2) or leave it temporally unqualified (the only thing we know is that it occurred) Database updates in EC provide information about the occurrences of events and their times [6] and are of additive nature only. We assume here that the set of events is fixed, and the input process consists in the addition of ordering information. We will show how the introduction of partial ordering heavily increases the computational complexity of deriving MVIs. Then, we will provide a ....

R. Kowalski 1992. "Database Updates in the Event Calculus", in Journal of Logic Programming 12, 121- 146.

....to temporal reasoning and study their relationship to the situation calculus. First, we look at the interval temporal logic [2, 3, 4, 5, 1] and discuss how its view of time can be, in most cases, modeled within the situation calculus. Second, we study in much greater detail the calculus of events [25, 24, 56], and argue that its formulation as a logic program has certain drawbacks. Also, we show that the functionality of the event calculus can be realized within the situation calculus. Furthermore, we present a logic program as an alternative to the logic programming formulation of the situation ....

Kowalski, R. Database Updates in the Event Calculus. The Journal of Logic Programming 12 (1992), 121--146.

....(e.g. 40, 20, 21, 27, 54, 33, 9, 47] So much so, that some researchers identify the frame problem as characteristic of theories based on the situation calculus, instead of as a problem inherent to the formalization of dynamic systems. Unfortunately, as has been pointed out elsewhere (e.g. [16, 23, 55]) the original situation calculus is a limited language that has several shortcomings. Nevertheless, as Gelfond, Lifschitz and Rabinov argue [16] these limitations can be overcome. The objective of this thesis is twofold. On the one hand, we want to extend the expressiveness of the situation ....

Kowalski, R. Database Updates in the Event Calculus. Tech. Rep. Doc 86/12, Imperial College, July 1986.

....sequences of update transactions. A wide variety of proposals for this exist in the literature (e.g. Abiteboul [1] Grahne [13] Katsuno and Mendelzon [20] Winslett [48] Fagin, Ullman and Vardi [10] Ginsberg and Smith [12] Guessoum and Lloyd [16, 17] Manchanda and Warren [32] Kowalski [22], Bonner and Kifer [6] In this paper, we advance a substantially different approach. To begin, we take seriously the fact that, during the course of its evolution, a database will pass through different states; accordingly, we endow updatable database relations with an explicit state argument ....

....of stating, for example, that a student s grade is unaffected by registering another student in a course, or by changing someone s address or telephone number or student number, etc. etc. The frame problem has been recognized in the setting of database transaction processing, notably by Kowalski [22] and Borgida, Mylopoulos and Schmidt [7] It is also implicit in various semantic approaches to database updates (but without appealing explicitly to transactions) such as the work of Grahne [13] Katsuno and Mendelzon [20] Grahne, Mendelzon and Revesz ( 14] and Winslett [48] Our approach ....

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R. Kowalski. Database updates in the event calculus. Journal of Logic Programming, 12:121--146, 1992.

....by macro expansion and second order constructs. Like in our ULTRA approach, all states generated by a sequence of actions are represented by an increment w.r.t. a certain initial state. The procedures that lead to the state transitions, however, are not specified in a rule formalism. Kowalski [Kow92] uses the event calculus for characterizing dynamics, which has some similarities with the situation calculus but behaves better for hypothetical reasoning. In [SWM93] a dynamic logic for verifying database updates is developed. However, the updates are programmed in a language like Embedded ....

R. Kowalski. Database updates in the event calculus. Journal of Logic Programming, 12:121--146, 1992.

....these ECA sublanguages and their interplay is formalized by means of deductive rules. More precisely, the database history (i.e. the ordered set of database states) is modeled using timestamped atoms, and the meaning of events, conditions, and actions is defined based on the event calculus in [Kow92] The approach has been used for the formalization of the active rule component which is added to the deductive object oriented database system ROCK ROLL [BFP 95] In contrast to Statelog and XY Datalog, which provide a single unified language for active and deductive rules, FWP97] ....

R. A. Kowalski. Database Updates in the Event Calculus. Journal of Logic Programming, 12(1&2):121--146, 1992.

....admits external events. Before moving on the the next supposed de ciency of the Situation Calculus, let us recall that it subsumes rst order logic. As such it allows the formation of complex action terms from simpler ones. This compositional potential has generally been overlooked (but see Kowalski 1986, Kowalski and Sergot 1986, and Morgenstern 1987) All of my remaining suggestions hinge on modifying or combining actions by means of functions. In the standard robot s world examples (including the ones herein) change occurs in quantum jumps. However, in formalizations based on the Situation ....

R.A. Kowalski, \Database updates in the event calculus," Technical Report DOC 86/12, Dept. of Computing, Imperial College, London, England, July 1986, 29 pages.

.... The Event Calculus was first defined in [18] as a formalism for representing and reasoning about the occurrence of events, the properties that events initiate and terminate, and the maximal time periods for which those properties hold [19] Further developments focused on a simplified variant [20,21,22,23,24,25,26] which employed time points instead of time periods. The key intuition of the simplified event calculus is that a property (in the world) holds if an event has happened to initiate it and, after the event, nothing has happened to terminate it. The occurrence of an event can initiate or terminate ....

Kowalski, R., "Database Updates in the Event Calculus", Journal of Logic Programming, Vol12, No.162, 1992, pp. 121-146.

....and ROLL, as described in [5] and [14] respectively. The active rule extension has two additional components which must be described, namely: 1. Event Definition Language: This has been described by way of a mapping onto deductive rules over an event history described using the event calculus of [20]. As an example, the event for the rule: RULE R1 WHEN aWire = EACH W putmaxvoltage(0) W] IF . COUPLING R1 CONDITION Immediate . gives rise to the following event rules: starts(EId, trigger( R1 , EId, W) event(EId) happened(EId, completed(put max voltage, W, wire, 0) ....

....and ROLL, as described in [5] and [14] respectively. The active rule extension has two additional components which must be described, namely: 1. Event Definition Language: This has been described by way of a mapping onto deductive rules over an event history described using the event calculus of [20]. As an example, the event for the rule: RULE R1 WHEN aWire = EACH W putmaxvoltage(0) W] IF . COUPLING R1 CONDITION Immediate . gives rise to the following event rules: starts(EId, trigger( R1 , EId, W) event(EId) happened(EId, completed(put max voltage, W, wire, 0) ....

R. Kowalski. Database updates in the event calculus. Journal of Logic Programming, 12:121--146, 1992.

....The second author was supported in part by NSF grant IRI9404629. Support from the Computer Systems Research Institute of University of Toronto is also gratefully acknowledged. 44 LOGICS FOR DATABASES AND INFORMATION SYSTEMS Notes 1. As opposed to using the Event Calculus to simulate updates [Kow92] 2. Additional information on T R, including a prototype implementation, is available at www.cs.toronto.edu bonner transaction logic.html 3. All our examples assume the non strict version of insert and delete, which means that executing p.ins at a state where p is true does not change the ....

R.A. Kowalski. Database updates in event calculus. Journal of Logic Programming, 12(1&2):121-146, January 1992.

....or applying a wider range of formulations of the Event Calculus. The Event Calculus was originally formulated as a logic program in [KoSe 86] and many alternative and extended logic program formulations have subsequently been proposed, including [DeMi 92] DeVa 96] KaMi 97] KaMi 99] Kowa 92] SaKo 95] Shan 90] VaDe 94a] VaDe 94b] VaDe 95] and [VaDe 96] The Event Calculus has also been formulated in modal logic in [CeCh 95] CeCh 96] CeFr 97a] CeFr 97b] CeFr 98] and [ChMo 94] as an action description language in [KaMi 97] and [KaMi 98] and in an argumentation ....

.... 97b] Shan 98] and [Jung 98] and in particular to cognitive robotics in [Shan 96a] Shan 96b] Shan 98] and [Shan 99b] Abduction in the context of the Event Calculus is also discussed in [DeMi 92] VaDe 94a] and [VaDe 94b] Other applications of the Event Calculus include database updates in [Kowa 92] and [VaDe 94b] accident report processing in [LeQu 98] and legal reasoning in [Kowa 95] Various formulations of Event Calculus have been extended to deal with continuous change and mathematical modelling in [MiSh 96] Shan 90] and [VaDe 94a] to deal with ramifications in [DeTh 98] KaMi ....

R. A. Kowalski, Database Updates in the Event Calculus, Journal of Logic Programming, vol. 12, pp. 121-146, 1992.

....Thus, the attributes (or type) of a material depend on the history of the material, as well as its class. This rather dynamic feature reflects the flexibility demanded by workflow management, and is closely related to research on time and action in artificial intelligence and logic programming [31, 30, 36, 44]. These issues are addressed in detail in Section 7, where we introduce structures that allow the view to be defined independently of the workflow, so that the view definition does not have to be changed each time the workflow changes. In addition to views, the database must support historical ....

....class. The schema of a material instance depends not only on its class, but also on its history. It is worth noting that deriving most recent values for materials is similar to certain problems of time and action in logic programming and artificial intelligence. For instance, the event calculus [31, 30] is a logic programming methodology developed for recording and querying event histories. It includes special access structures to quickly retrieve most recent results. As another example, the situation calculus [36, 44] encodes event histories as function terms. Queries in the situation calculus ....

R.A. Kowalski. Database updates in the event calculus. Journal of Logic Programming (JLP), 12(1&2):121--146, January 1992.

....of backward persistence of properties and preprocessing away all reference to time periods. We do the latter by replacing all conditions referring to properties holding for time periods by their definition in terms of events happening at time points. Such a special case was introduced in ([10], 5] 18] In [17] we showed that this special case, in completion form augmented with integrity constraints, has much of the power of the original event calculus, and even overcomes some of its deficiencies. The special case of the event calculus has at its core a single axiom: holds(P, T2) ....

Kowalski R.A., Database updates in the event calculus, Journal of Logic Programming 12:121-146 (1992).

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R. Kowalski: "Database Updates in the Event Calculus", in Journal of Logic Programming, Vol. 12, June 1992, pp 121-146.

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Kowalski, R.A., Database updates in event calculus. Journal of Logic Programming, Vol.12, pp.121-146, January 1992.

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R. Kowalski. Database updates in the event calculus. Journal of Logic Programming, 12:121--146, 1992.

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R. Kowalski. Database updates in the event calculus. The Journal of Logic Programming, 12:121, January 1992.

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R. Kowalski. Database updates in the event calculus. The Journal of Logic Programming, 12:121, January 1992.

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R. Kowalski. Database updates in the event calculus. The Journal of Logic Programming, 12:121, January 1992.

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Kowalski, R.A.: Database updates in the event calculus. J. Logic Programming (1992) 121--146

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Kowalski R., Database Updates in the Event Calculus, Journal of Logic Programming, 12:121-146, 1992.

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