Evans C., The Macro-Event Calculus: Representing Temporal Granularity, Proc. PRICAI90, 1990.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....[JCE 94] it is something that happens, rather than being true over time . Events delimit states. The We do not consider the so called macro events that are true, or take place, for an interval of time, but are not true for any subset of their interval. A wedding is an example [Eva90, MMCR92] occurrence of an event results in a fact becoming true; later, the occurrence of another event renders that fact no longer valid. Hence, events and states are duals; states can be represented by their delimiting events, and events are implied by states. A conventional relation models ....

C. Evans. The Macro-Event Calculus: Representing Temporal Granularity. In Proceedings of PRICAI, Tokyo, Japan, 1990.

....by ONR grant N00014 97 1 0505, Multidisciplinary University Research Initiative Semantic Consistency in Information Exchange. been addressed in [CMP93, CMP94, DMB92, Esh88, Sha89] primitives for dealing with continuous change, discrete processes, and concurrent actions have been proposed in [Eva90, MMCR92, Sha90]; preconditions have been incorporated in di#erent variants of basic EC [CFM97b] However, a uniform framework that allows formally defining and contrasting the expressiveness and complexity of the various extensions to EC is still lacking. In this paper, we unify some of this previous work and ....

Chris Evans. The macro-event calculus: Representing temporal granularity. In Proceedings of the Pacific Rim International Conference on Artificial Intelligence --- PRICAI'90, Nagoya, Japan, 1990. IOS Press. 31

....simultaneous actions and of incomplete knowledge on action occurrences, action ordering or the initial state of the world. The language allows for change propagations not related to state (or 34 An alternative but equivalent view is that the turning on of the lamp is a macro action (as defined in [8]) which can consist of either of the primitive actions. Deriving a primitive action which satisfies the conditions of the macro action is also a typical abductive task. 61 more general) constraints between fluents, and for recursion and cycles in the rules describing change propagation. We have ....

C. Evans. The Macro-Event Calculus: Representing Temporal Granularity. In Proceedings of PRICAI, Tokyo, 1990.

....have extended it with abduction for the purpose of planning. 31] extended event calculus to deal with necessary preconditions of actions. 25] implemented a planning system based on this formalism. Other work has been done to extend event calculus with continuous actions [32] and time granularity [15], 26] Recently [10] applied abductive event calculus to solve a number of benchmark problems in temporal reasoning, such as the Murder Mystery, the Stolen Car problem, the Walking Turkey Shooting problem and the Russian Turkey Shooting problem. The latter problem contains an indeterminate ....

C. Evans. The Macro-Event Calculus: Representing Temporal Granularity. In Proc. of PRICAI, Tokyo, 1990. 27

....have extended it with abduction for the purpose of planning. 21] extended event calculus to deal with necessary preconditions of actions. 17] implemented a planning system based on this formalism. Other work has been done to extend event calculus with continuous actions [22] and time granularity [11], 18] Recently [8] applied abductive event calculus to solve a number of benchmark problems in temporal reasoning, such as the Murder Mystery, the Stolen Car problem, the Walking Turkey Shooting problem and the Russian Turkey Shooting problem. The latter problem contains an indeterminate action. ....

C. Evans. The Macro-Event Calculus: Representing Temporal Granularity. In Proc. of PRICAI, Tokyo, 1990.

....relation at that time. For example, the timeslice at time Wednesday yields the relation in Figure 1(b) ut 2 We do not consider the so called macro events that are true, or take place, for an interval of time, but are not true for any subset of their interval. A wedding is an example [Eva90, MMCR92] 3 Name Dept Time Tom Shipping Monday Tuesday Kate Loading Monday Thursday Sam Shipping Wednesday now (a) Name Dept Kate Loading Sam Shipping (b) Figure 1: A Sample Temporal Relation (a) and a Timeslice (b) The question we asked was, is the temporal relation a ....

C. Evans. The Macro-Event Calculus: Representing Temporal Granularity. In Proceedings of PRICAI, Tokyo, Japan, 1990.

....contrast, the transaction time of a 2 We do not consider the so called macro events that are true, or take place, for an interval of time, but are not true for any subset of their interval. A wedding is an example, as the first, say, 20 minutes of a wedding macro event is not itself a wedding [11, 35]. SEMANTICS OF TIME VARYING INFORMATION 37 fact cannot extend beyond the current time (there is no foolproof way of knowing whether the fact will be current in the database in the future) and the transaction time cannot be changed (we cannot now change what was stored in the database in the ....

C. Evans. The Macro-Event Calculus: Representing Temporal Granularity. In Proceedings of PRICAI, Tokyo, Japan (1990).

.... work on process modeling, which inspired research in many Computer Science areas, including knowledge representation, has been done by Hoare [15] and Milner [21] Limited contributions to (discrete) process modeling in the temporal representation and reasoning area have been proposed by Evans [12], Belegrinos and George [6] Lesp erance et al. 17] and by Lin and Dean [19] In this paper, we present preliminary results on the de nition of a Macro Event Calculus, an extension of Kowalski and Sergot s Event Calculus, EC [16] Our proposal allows expressing basic forms of process ....

....j m (Iteration) where d; D 2 T and d D. Let M T be the set of the macro events over T . This de nition formalizes the core of the notion of process studied at length in [10, 22] which in turn extends the limited notion of macro events (essentially delayed sequencing) presented in [12]. The constructors we included in this language are based on the path expression operators of [3] and on the process calculi operators found in [15, 21] Observe that a number of useful constructs are easily expressible with the language in De nition 4.1. In particular sequencing with arbitrary ....

C. Evans. The macro-event calculus: Representing temporal granularity. In Proceedings of the Paci c Rim International Conference on Articial Intelligence | PRICAI'90, Nagoya, Japan, 1990. IOS Press.

....can be adapted in a natural way to deal with versioning of objects and schema evolution respectively. The literature on temporal reasoning and temporal databases is very extensive and we do not attempt a full survey here. For various extensions and applications of the event 3 calculus see, e.g. [11, 15, 20, 23, 24, 51, 54, 59, 62, 65]. Comparisons of the event calculus with situation calculus are provided in [53] and [45] For temporal databases, 43] provides a recent bibliography of work in this area together with pointers to previous bibliographies. The collection [69] gives an excellent overview of the main approaches and ....

....to formulate within the OEC, since it is continuous change of values of attributes that is of interest; it is difficult to imagine what continuous change of membership of a class would correspond to. Other extensions, such as allowing for different granularities of time within the same data model [24, 51], could also be adapted straightforwardly. In the database field, the modelling of temporal information has been dominated by approaches based on the relational model. There are exceptions (see e.g. 21, 32, 56, 57, 68, 73] and [61] for a comparative survey) These proposals differ in the range ....

C. Evans. The Macro-Event Calculus: Representing Temporal Granularity. In Proceedings Pacific Rim International Conference on AI, Nagoya, Japan, 1990, pp363-- 368.

....OEC can be adapted in a natural way to deal with versioning of objects and schema evolution respectively. The literature on temporal reasoning and temporal databases is very extensive and we do not attempt a full survey here. For various extensions and applications of the event calculus see, e.g. [11, 15, 19, 22, 23, 48, 51, 56, 58, 61]. Comparisons of the event calculus with situation calculus are provided in [50] and [43] For temporal databases, 41] provides a recent bibliography of work in this area together with pointers to previous bibliographies. The collection [65] gives an excellent overview of the main approaches ....

....formulate within the OEC, since it is continuous change of values of attributes that is of interest; it is difficult to imagine what continuous change of membership of a class would correspond to. Other extensions, such as allowing for different granularities of time within the same data model [23, 48], could also be adapted straightforwardly. In the database field, the modelling of temporal information has been dominated by approaches based on the relational model. There are exceptions (see e.g. 31, 53, 54, 64] A recent example is the extended entity relationship model described in [20] ....

C. Evans. The Macro-Event Calculus: Representing Temporal Granularity. In Proceedings Pacific Rim International Conference on AI, Nagoya, Japan, 1990, pp363-- 368.

....edges of this appealing framework. y We do not consider the so called macro events that are true, or take place, for an interval of time, but are not true for any subset of their interval. A wedding is an example, as the first, say, 20 minutes of a wedding macro event is not itself a wedding [21, 58]. 36 Jensen and Snodgrass 2.1. Temporal Specialization While valid time and transaction time had been shown to be orthogonal [79] some papers did not make a distinction between the two. Instead, they seemed to use one time to handle both aspects. For example, the POSTGRES papers mentioned ....

C. Evans. The Macro-Event Calculus: Representing Temporal Granularity. In Proceedings of PRICAI, Tokyo, Japan (1990).

....(see [14] is a well known formalism for temporal representation and reasoning. The basic concepts of the formalism are events and properties: events initiate and terminate periods of time during which properties hold. The Event Calculus has been modified in several ways, for example in [20] [9], 17] and [13] mainly to simplify the ontology and to eliminate problems occurring because of bidirectional persistence of properties (forward as well as backward in time) In the context of the Event Calculus, 8] 19] and [17] have introduced abduction to solve planning problems and [7] ....

C. Evans. The Macro-Event Calculus: Representing Temporal Granularity. In Proceedings of PRICAI, Tokyo, 1990.

....(see [ 12 ] is one of the many formalisms used for representing a changing world. The basic concepts are events and properties, events initiating and terminating periods of time during which properties hold. Several modified versions of the Event Calculus have been used, for example in [ 19 ] [ 9 ] and [ 15 ] mostly to simplify the ontology and to eliminate problems occuring because of bidirectional persistence of properties (forward as well as backward in time) Extensions were introduced to improve the expressive power in several ways. One of the most important of these was the ....

C. Evans. The Macro-Event Calculus: Representing Temporal Granularity. In Proceedings of PRICAI, Tokyo, 1990.

....have extended it with abduction for the purpose of planning. 30] extended event calculus to deal with necessary preconditions of actions. 25] implemented a planning system based on this formalism. Other work has been done to extend event calculus with continuous actions [31] and time granularity [15], 26] Recently [10] applied abductive event calculus to solve a number of benchmark problems in temporal reasoning, such as the Murder Mystery, the Stolen Car problem, the Walking Turkey Shooting problem and the Russian Turkey Shooting problem. The latter problem contains an indeterminate ....

C. Evans. The Macro-Event Calculus: Representing Temporal Granularity. In Proc. of PRICAI, Tokyo, 1990.

.... the consequence of events using the logic based event calculus can be found in [KS86] Chi94] The idea of structuring ordering and causal knowledge to speed up temporal reasoning is also present in maintaining knowledge about temporal intervals [All83] GS93] KG77] and in the event calculus [Eva90] Mea92] The use of subgoals and abstract events in Chaprer 4 is inspired by the similar notions of subgoals and abstraction used in search [Kor87] and in abstract and hierarchical planning [Sac74a] Chr90] Kno91a] YT90] in reducing the overall search effort. The idea of using localized ....

C. Evans. The macro-event calculus: Representing temporal granularity. In Proceedings of PRICAI'90, 1990.

.... the consequence of events using the logic based event calculus can be found in [KS86] Chi94] The idea of structuring ordering and causal knowledge to speed up temporal reasoning is also present in maintaining knowledge about temporal intervals [All83] GS93] KG77] and in the event calculus [Eva90] [Mea92] The use of subgoals and abstract events in this paper is inspired by the similar notions of subgoals and abstraction used in search [Kor87] and in abstract and hierarchical planning [Sac74] Chr90] Kno91] YT90] in reducing the overall search effort. The idea of using localized ....

C. Evans. The macro-event calculus: Representing temporal granularity. In Proceedings of PRICAI'90, 1990.

....time from each other. It is worth noting that the ordering rests defined by the time line. In particular, in admitting these forms of temporal displacements we commit to a specific metric of time. Albeit EC has been upgraded for dealing with changing time granularities, the results, as those in [7, 12], are not discussed here. An examination of the axioms of EC from Section 2 shows that Date and Before only are needed for computing intervals. Therefore, the axioms of ordering, that will be given in the next section, will be tailored for deriving ordering information in the form of Before ....

C. Evans, The Macro-Event Calculus: Representing Temporal Granularity. in Artificial Intelligence in the Pacific Rim. Proceedings of PRICAI'90 Conference, Nagoya, Japan, IOS Press, 1991.

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Evans C., The Macro-Event Calculus: Representing Temporal Granularity, Proc. PRICAI90, 1990.

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