A. Montanari, E. Maim, E. Ciapessoni, E. Ratto: "Dealing with Time Granularity in the Event Calculus", in Proc. of FGCS'92 Conference, Tokyo, Japan, June 1992, pp 702-712.  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occurrence of an event results in a fact becoming true; later, the occurrence of another event renders that fact no longer valid.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 the ....

A. Montanari, E. Maim, E. Ciapessoni, and E. Ratto. Dealing with Time Granularity in the Event Calculus. In Proceedings of the International Conference on Fifth Generation Computer Systems 1992, volume 2, pages 702--712, Tokyo, Japan, June 1992.

....Sunday is (1998, 7, 2) 6. Related Work Much work has been done on the problem of granularity representation in temporal database area as well as other areas like arti cial intelligence and real time systems. Some of them address the formalization of time granularity systems [BWJ98,CR87,Dea89,MMCR92] Our work is an instantiation of the general framework proposed in [BWJ98] A symbolic representation of granularities that allows natural language expression was proposed in [LMF86] on the basis of structured collections of inter Ning, Wang and Jajodia An Algebraic Representation of ....

A. Montanari, E. Maim, E. Ciapessoni, and E. Ratto. Dealing with time granularity in the event calculus. In Proc. of the Int. Conf. on Fifth Generation Computer Systems, pages 702-712, Tokyo, Japan, 1992. Ning, Wang and Jajodia / An Algebraic Representation of Calendars 41

....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 action. ....

A. Montanari, E. Maim, E. Ciapessoni, and E. Ratto. Dealing with Time Granularity in the Event Calculus. In Proc. of the International Conference on Fifth Generation Computer Systems, pages 702--712, 1992.

....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. ....

A. Montanari, E. Maim, E. Ciapessoni, and E. Ratto. Dealing with Time Granularity in the Event Calculus. In Proc. of the International Conference on Fifth Generation Computer Systems, pages 702--712, 1992.

....the proper handling of granularity mismatches in operations between temporal primitives with different granularities. This usually requires converting a temporal primitive from one granularity to another. Although there have been various recent proposals that handle multiple granularities [15, 11, 10, 13], the focus has been on representing anchored temporal primitives that are specified in different granularities. Granularity conversions are given for anchored temporal primitives only. However, we contend that supporting unanchored temporal primitives with different granularities is equally ....

....unanchored temporal primitives to be specified in different and mixed granularities, and facilitates the conversion of unanchored temporal primitives from one granularity to another. The inherent problem in adequately supporting unanchored temporal primitives with different granularities in [15, 11, 10, 13], is that a granularity is treated as an anchored partitioning of the time axis. Since unanchored temporal primitives are independent of anchored temporal primitives (i.e. their location on the time axis is unknown since they are not anchored at any particular point) problems arise in the ....

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A. Montanari, E. Maim, E. Ciapessoni, and E. Ratto. Dealing with Time Granularity in Event Calculus. In Proceedings of the International Conference on Fifth Generation Computer Systems, pages 702--712, June 1992.

.... in an inconsistent constraint network is ffalseg (i.e. not satisfiable) 5 Related work A first formalization of a time granularity system is probably that of [CR87] However, the system proposed in [CR87] as well as most of the time granularity systems proposed in the literature (e.g. [Dea89, MMCR92]) is quite restrictive. For example, these systems often impose a total order on granularities. The restrictions are usually motivated by useful formal and computational properties that can be achieved with them. In [Dea89] a time granularity system is introduced and the author shows how it can ....

....incomparable types. In terms of our formal model it could be characterized by using a finite subset of integers for both absolute time and index set with only restriction (1) on the structure of ticks. Relevant work on time granularities has been done also in other areas like logic programming [MMCR92], and real time system specification [CCMP93] In these papers the emphasis is on embedding these notions into a logical formalism. The granularity system proposed in [MMCR92] can be described in our framework exactly as the one discussed above for [Dea89] with the extra restriction (4) of equal ....

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A. Montanari, E. Maim, E. Ciapessoni, and E. Ratto, Dealing with time granularity in the event calculus, in Proc. of the Int. Conf. on Fifth Generation Computer Systems, Tokyo, Japan, 1992, pp. 702--712. 25

....objects. We also employ a sliding rule paradigm to support navigation through multiresolutional data. Related work has been performed in identifying and formalizing operations in the temporal domain in order to support the integration of different databases [3] and also on granularity issues [10,14]. Our approach is novel as it incorporates the concept of granularity in the query process of a spatiotemporal model. In spatiotemporal systems resolution cannot be considered static, since change resolution is defined by the query in real time mode. Our system s structure supports these ....

A. Montanari, E. Maim, E. Ciapessoni, and E. Ratto, "Dealing with Time Granularity in the Event calculus", In Proceedings of the International Conference on Fifth Generation Computer Systems 1992, volume 2, Tokyo, Japan, 1992, pp. 702-712.

.... problems would arise both in integrating data from heterogeneous systems based on di erent time units, and in converting a temporal primitive from some granularity to that of the system (e.g. 3 months in days) Although there have been various recent proposals that handle multiple granularities [2, 4, 7, 11, 21, 22, 23, 25, 26, 27], the focus has been mainly on representing anchored temporal primitives that are speci ed in di erent granularities. Granularity conversions are given for anchored temporal primitives only. However, supporting unanchored temporal primitives with di erent granularity is equally important [18] All ....

....time spans Since a time span is independent of any time instant or time interval due to its relative nature, granularity conversions in the context of anchored temporal primitives cannot be used for unanchored temporal primitives. Hence, most of the 19 previously described temporal models [4, 7, 21, 22, 23, 25, 26, 27] cannot support completely the unanchored temporal information needs of an application like the clinical example given in Section 1.1. Although the work of Lorentzos [20] does not explicitly deal with temporal granularity, it proposes a scheme for representing and operating on non metric types. ....

[Article contains additional citation context not shown here]

A. Montanari, E. Maim, E. Ciapessoni, and E. Ratto. Dealing with Time Granularity in Event Calculus. In Proceedings of the International Conference on Fifth Generation Computer Systems, IOS Press, Tokyo, 702-712, 1992.

....and discrete domains of time. This allows a temporal model to provide support not only for applications which usually need a discrete temporal domain, but also for applications that need dense time as an abstraction. This is in contrast to recent proposals that handle multiple granularities [4, 13, 5, 18, 2, 17, 15]. These proposals assume a single underlying temporal domain which is usually discrete. The contributions of this paper can be summarized as follows: 1) We present a simple, general framework for supporting temporal primitives which allows seamless integration of dense and discrete domains of ....

A. Montanari, E. Maim, E. Ciapessoni, and E. Ratto. Dealing with Time Granularity in Event Calculus. In Proceedings of the International Conference on Fifth Generation Computer Systems, pages 702--712, June 1992.

....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 valid time ....

A. Montanari, E. Maim, E. Ciapessoni, and E. Ratto. Dealing with Time Granularity in the Event Calculus. In Proceedings of the International Conference on Fifth Generation Computer Systems 1992, volume 2, pages 702--712, Tokyo, Japan, June 1992. ICOT.

....modeling the basic temporal entities. The few works that 2 Citation Calendar(s) Granularities Time primitives Granularity conversions [CR87] No support Multiple Anchored Anchored [WJL91] WJS93] No support Multiple Anchored Anchored [BP85] MPB92] No support Multiple Anchored Anchored [MMCR92] No support Multiple Anchored Anchored [Sno95b] Multiple Multiple Anchored Unanchored Anchored Table 1: Temporal models supporting calendars and or granularities have appeared in this area have concentrated mainly on modeling anchored temporal entities. We contend that unanchored temporal ....

....Operands (which are anchored) in operations involving mixed granularities are converted to the coarser granularity to avoid indeterminacy. In a more recent work [MPB92] the existence of a minimum underlying granularity (quantum of time) to which time is mapped, is assumed. Montanari et al. MMCR92] examined the issue of multiple granularities, but considered exact granularity conversions only. In [CSS94] structured collections of time intervals are defined and termed as calendars. Corsetti et al. CMR91] deal with different time granularities in specifications of real time systems. ....

A. Montanari, E. Maim, E. Ciapessoni, and E. Ratto. Dealing with Time Granularity in Event Calculus. In Proceedings of the International Conference on Fifth Generation Computer Systems, pages 702--712, June 1992.

....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 ....

A. Montanari, E. Maim, E. Ciapessoni, and E. Ratto. Dealing with Time Granularity in the Event Calculus. In Proceedings of the International Conference on Fifth Generation Computer Systems 1992, pp. 702--712, Tokyo, Japan (1992).

....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 ....

A. Montanari, E. Maim, E. Ciapessoni, E. Ratto. Dealing with Time Granularity in the Event Calculus. In Proceedings of the Fifth Generation Computer Systems Conference FGCS'92, Tokyo, 1992, pp702--712.

....a practical design for that support. We see the following as the seven main contributions of this paper. First, various semantics have been proposed for temporal operations that have operands at different granularities [Adiba et al. 1985, Cli ord Rao 1987, Lorentzos 1992, Melton Simon 1993, Montanari et al. 1992, Sarda 1993, Wang et al. 1995, Wiederhold et al. 1991] For instance, in a comparison operation between a time known to the granularity of days and one known to the granularity of hours, the comparison could be performed at days, or it could be done at hours, or an error could be reported. In ....

....then perform the operation to a granularity ner than both arguments. g h = 8 : g scale(h; G) if G is ner than H scale(g; H) h if G is coarser than H scale(g; F ) scale(h; F ) otherwise Coarser semantics Perform the operation to the coarser granularity [Barbic Pernici 1985, Montanari et al. 1992] For incomparable granularities, perform the operation to a granularity that is minimally coarser. This approach avoids adding indeterminacy not already present, but is, in some sense, the most conservative possibility, as information at the ner granularity is discarded. g h = 8 : ....

[Article contains additional citation context not shown here]

Montanari, A., E. Maim, E. Ciapessoni and E. Ratto. \Dealing with Time Granularity in the Event calculus," in Proceedings of the International Conference on Fifth Generation Computer Systems 1992. ICOT. Tokyo, Japan: June 1992, pp. 702-712.

....a practical design for that support. We see the following as the seven main contributions of this paper. First, various semantics have been proposed for temporal operations that have operands at different granularities [Adiba et al. 1985, Clifford Rao 1987, Lorentzos 1992, Melton Simon 1993, Montanari et al. 1992, Sarda 1993, Wang et al. 1995, Wiederhold et al. 1991] For instance, in a comparison operation between a time known to the granularity of days and one known to the granularity of hours, the comparison could be performed at days, or it could be done at hours, or an error could be reported. In ....

.... time is viewed as being isomorphic to the real numbers, with each real number corresponding to a time point, the dense model, in which time is viewed as being isomorphic to the rationals, or the discrete model, in which time is viewed as being isomorphic to the integers [Clifford Rao 1987, Montanari et al. 1992] Science and metaphysics have yet to determine which model best fits reality; good arguments can be made for each model (e.g. some quantum theories view time as ultimately quantized or discrete [Anderson 1982] We abstain from choosing amongst these three models. In our model, time can be ....

[Article contains additional citation context not shown here]

Montanari, A., E. Maim, E. Ciapessoni and E. Ratto. "Dealing with Time Granularity in the Event calculus," in Proceedings of the International Conference on Fifth Generation Computer Systems 1992. ICOT. Tokyo, Japan: June 1992, pp. 702--712.

....commonly have operands at different granularities. For instance, a comparison operation might compare a time known to the granularity of a day to a time known to the granularity of an hour. Various semantics have been proposed for temporal operations on mixed granularities [ABQPdO85, CR87, MS93, MMCR92, Sar93, WJS93, WJL91] In this paper we propose two simple operations that can be utilized to support all of the previous semantics for temporal operations. Second, some useful granularities are nonmetric or irregular measurement schemes. For example, in the Gregorian calendar, the ....

....know that it is located sometime during a 1440 minute period. ffl Perform the operation to the coarser granularity. This approach avoids adding indeterminacy not already present, but is in some sense the most conservative possibility, as information at the finer granularity is discarded [BP85, MMCR92] We can show that all these semantics (save generating an error) rest on operations that move times within the granularity graph. In all the proposed semantics the operands are first converted to the same granularity, and then the operation is carried out. Below we describe operations that ....

[Article contains additional citation context not shown here]

A. Montanari, E. Maim, E. Ciapessoni, and E. Ratto. Dealing with Time Granularity in the Event calculus. In Proceedings of the International Conference on Fifth Generation Computer Systems 1992, volume 2, pages 702--712, Tokyo, Japan, June 1992. ICOT.

....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] ....

A. Montanari, E. Maim, E. Ciapessoni, E. Ratto. Dealing with Time Granularity in the Event Calculus. In Proceedings of the Fifth Generation Computer Systems Conference FGCS'92, Tokyo, 1992, pp702--712.

....in the constraint network. The algorithm may derive tighter constraints (in the sense of logical implication) if additional temporal types are used. 4 Related work Most of the time granularity systems proposed in the literature are quite restrictive, often imposing a total order on granularities [CR87, Dea89, MMCR92]. 2 The conversion must guarantee that a logically implied constraint exists in the target granularity. We use the sufficient condition that the set of time instants corresponding to the source granularity must be a subset of that corresponding to the target granularity. The restrictions are ....

....ticks and incomparable types. In terms of our formal model it could be characterized by using a finite subset of integers for both absolute time and index set with only restriction (1) on the structure of ticks. Relevant work on this subject has been done also in other areas like logic programming [MMCR92], and real time system specification [CCMP93] In these papers the emphasis is on embedding these notions into a logical formalism. The granularity system proposed in [MMCR92] can be described in our framework exactly as the one discussed above for [Dea89] with the extra restriction (4) of equal ....

[Article contains additional citation context not shown here]

A. Montanari, E. Maim, E. Ciapessoni, and E. Ratto. Dealing with time granularity in the event calculus. In Proc. of the Int. Conf. on Fifth Generation Computer Systems 1992, volume 2, pages 702--712, Tokyo, Japan, June 1992. ICOT.

....and discrete domains of time. This allows a temporal model to provide support not only for applications which usually need a discrete temporal domain, but also for applications that need dense time as an abstraction. This is in contrast to recent proposals that handle multiple granularities [4, 13, 5, 18, 2, 17, 15]. These proposals assume a single underlying temporal domain which is usually discrete. The contributions of this paper can be summarized as follows: 1) We present a simple, general framework for supporting temporal primitives which allows seamless integration of dense and discrete domains of ....

A. Montanari, E. Maim, E. Ciapessoni, and E. Ratto. Dealing with Time Granularity in Event Calculus. In Proceedings of the International Conference on Fifth Generation Computer Systems, pages 702--712, June 1992.

No context found.

A. Montanari, E. Maim, E. Ciapessoni, E. Ratto: "Dealing with Time Granularity in the Event Calculus", in Proc. of FGCS'92 Conference, Tokyo, Japan, June 1992, pp 702-712.

....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 ....

Angelo Montanari, Enrico Maim, Emanuele Ciapessoni, and Elena Ratto. Dealing with time granularity in the event calculus. In Proceedings of the International Conference on Fifth Generation Computer Systems --- FGCS'92, pages 702--712, Tokyo, Japan, 1--5 June 1992.

.... the addition of modal capabilities to EC has been addressed in (Cervesato et al. 1993; Chittaro et al. 1994; Denecker et al. 1992; Eshghi, 1988; Shanahan, 1989) primitives for dealing with continuous change, discrete processes, and concurrent actions have been proposed in (Evans, 1990; Montanari et al. 1992; Shanahan, 1990) preconditions have been incorporated in di erent variants of the basic EC (Cervesato et al. 1997b) However, a uniform framework that allows formally de ning and contrasting the expressiveness and complexity of the various extensions to EC is still lacking. In this paper, we ....

A. Montanari, E. Maim, E. Ciapessoni, and E. Ratto. Dealing with time granularity in the event calculus. In Proceedings of the International Conference on Fifth Generation Computer Systems | FGCS'92, pages 702-712, Tokyo, Japan, 1-5 June 1992.

....of kernel of an ordering relation, and show that it can be usefully applied to further reduce the complexity of computing MVIs. 1 Introduction Kowalski and Sergot s Event Calculus (EC) is a formalism for representing and reasoning about events and their effects in a logic programming framework [3, 7, 9, 10, 11]. Given a set of events occurring in the real world, EC is able to infer the set of maximal validity intervals (MVIs, hereinafter) over which the properties initiated and or terminated by the events maximally hold. Event occurrences can be provided with different temporal qualifications [1] In ....

A. Montanari, E. Maim, E. Ciapessoni, E. Ratto: "Dealing with Time Granularity in the Event Calculus", in Proc. of FGCS'92, Tokyo, Japan, June 1992, pp 702-712.

....modal counterparts of EC. It is then shown how a full propositional modal logic based on these calculi can be conveniently and elegantly coded by means of the linear logic programming language Lolli. 1 1 Introduction This paper studies the formalization of Kowalski and Sergot s Event Calculus [3, 9, 16, 17, 19, 20] (hereinafter EC) in cases where information about the ordering of events is incomplete [1, 18] This situation arises in many real world applications (e.g. 11] Complete ordering information can be impossible to acquire or it can arrive asynchronously with respect to the recording of event ....

A. Montanari, E. Maim, E. Ciapessoni, E. Ratto: "Dealing with Time Granularity in the Event Calculus", in Proc. of FGCS'92 Conference, Tokyo, Japan, June 1992, pp 702-712.

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A. Montanari, E. Maim, E. Ciapessoni, and E. Ratto. Dealing with Time Granularity in Event Calculus. In Proceedings of the International Conference on Fifth Generation Computer Systems, pages 702--712, June 1992.

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