H. Gregersen and C. S. Jensen. Conceptual Modeling of Time-varying Information. In Proceedings of International Conference on Computing, Communications and Control Technologies, pages 248--255, August 2004.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....extended conceptual data models developed to abstract the temporal aspects of information. Without loss of generality, we will specifically refer to a general temporal ER model, and we will consider it as capturing the relevant common features of the models introduced by the systems TimeER [27], ERT [42] MADS [40] These models cover the full spectrum of temporal constructs Employee s Name(String) s PaySlipNumber(Integer) Salary(Integer) vt Project ProjectCode(String) Manager vt TopManager AreaManager Department s InterestGroup OrganisationalUnit s d DEX Works for vt ....

.... are distinguished between snapshot participation constraints true at each point in time and represented by a pair of values in parentheses and lifespan participation constraints evaluated during the entire existence of the entity and represented by a pair of values in square brackets [41,27,40]. Fig. 1 gives a diagram showing the various temporal constructs, and will form a running example trough the Chapter. Dynamic relationships between entities [40] can be either transition or generation relationships. In a transition relationship the instances of an entity may eventually become ....

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H. Gregersen and J.S. Jensen. Conceptual modeling of time-varying information. Technical Report TimeCenter TR-35, Aalborg University, Denmark, 1998.

.... the temporal description logic DLRUS can provide a formal semantic characterisation of the most important temporal conceptual modelling constructs (for the valid time representation) We refer mostly to the temporal extended entity relationship data model, for which a detailed literature exists [25, 24, 41, 44]. We consider the following constructs: snapshot and temporary entities, relationships, attributes (together with the temporal key attribute) temporal cardinalities, dynamic entities, liveliness and safety constraints, and the monotonic form of schema evolution. The extended entity relationship ....

....formula for PaySlipNumber in Sect. 2.3) Temporal cardinalities. Cardinality constraints limit the participation of entities in relationships. In a temporal setting, we can distinguish between snapshot participation constraints (true at each point in time) and lifespan participation constraints [43, 25, 41] (evaluated during the entire existence of the entity) While the standard DLRUS cardinality construct captures snapshot participation constraints, the lifespan participation constraints are defined by the following DLRUS formula: 7n [i]3 R i.e. over its lifespan, an instance of the ....

H. Gregersen and J.S. Jensen. Conceptual modeling of time-varying information. Technical Report TimeCenter TR-35, Aalborg University, Denmark, 1998.

.... see [4] To illustrate the expressive power of DLRUS , we provide a formal semantic characterisation by means of DLRUS theories of the most important temporal conceptual modelling constructs (for the valid time representation) appeared in the literature on the entityrelationship data model [18, 17, 35, 3]. To the best of our knowledge, this is the first systematic formalisation of the constructs present in the majority of temporal conceptual modelling systems. The outcome is an elegant correspondence between temporal constructs and sets of DLRUS formulas. Moreover, temporal integrity constraints ....

....# = Q 2 # Q 1 . 3 Conceptual modelling with DLR US In this section we show how the temporal description logic DLRUS can provide a formal semantic characterisation of the most important temporal conceptual modelling constructs (for the valid time representation) appeared in the literature [18, 17, 35]. This characterisation allows us to define and support several forms of reasoning about both temporal conceptual models and temporal queries by using the reasoning services of DLRUS . 3.1 The implicit entity relationship model The extended entity relationship (EER) model 4 may be viewed as ....

[Article contains additional citation context not shown here]

H. Gregersen and J.S. Jensen. Conceptual modeling of time-varying information. Technical Report TimeCenter TR-35, Aalborg University, Denmark, 1998.

.... see [4] To illustrate the expressive power of DLRUS , we provide a formal semantic characterisation by means of DLRUS theories of the most important temporal conceptual modelling constructs (for the valid time representation) appeared in the literature on the entityrelationship data model [18, 17, 35, 3]. To the best of our knowledge, this is the first systematic formalisation of the constructs present in the majority of temporal conceptual modelling systems. The outcome is an elegant correspondence between temporal constructs and sets of DLRUS formulas. Moreover, temporal integrity constraints ....

....2 and j= Q 2 Q 1 . 3 Conceptual modelling with DLR US In this section we show how the temporal description logic DLRUS can provide a formal semantic characterisation of the most important temporal conceptual modelling constructs (for the valid time representation) appeared in the literature [18, 17, 35]. This characterisation allows us to define and support several forms of reasoning about both temporal conceptual models and temporal queries by using the reasoning services of DLRUS . 3.1 The implicit entity relationship model The extended entity relationship (EER) model 4 may be viewed as a ....

[Article contains additional citation context not shown here]

H. Gregersen and J.S. Jensen. Conceptual modeling of time-varying information. Technical Report TimeCenter TR-35, Aalborg University, Denmark, 1998.

....properties. This paper reports the results of this attempt. This paper provides a formal semantic characterisation by means of theories in the T DLR temporal logic of the most important temporal conceptual modelling constructs (for valid time representation) as found in the literature [Gregersen and Jensen, 1998; 1999; Spaccapietra et al. 1998] To the best of our knowledge, this is the first systematic formalisation of the constructs present in most temporal conceptual modelling systems. The outcome is an elegant correspondence between temporal constructs and sets of T DLR axioms, so that a ....

....Explicit Temporal Constructs In the following it will be showed how T DLR axioms can be used to formalise and encode the various explicit temporal constructs appeared in the literature on temporal conceptual models. We will consider the explicit temporal constructs surveyed in the overview papers [Gregersen and Jensen, 1998; 1999; Spaccapietra et al. 1998] The ability to add temporal constructs on top of a temporally implicit model has the advantage of preserving the atemporal semantics of conventional (legacy) EER schemas when embedded into temporal EER diagrams: this property is called upward compatibility. The ....

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H. Gregersen and J.S. Jensen. Conceptual modeling of time-varying information. Technical Report TimeCenter TR-35, Aalborg University, Denmark, 1998.

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H. Gregersen and C. S. Jensen. Conceptual Modeling of Time-varying Information. In Proceedings of International Conference on Computing, Communications and Control Technologies, pages 248--255, August 2004.

No context found.

Gregersen, H., and Jensen, C., 1998. Conceptual Modeling of Time-Varying Information. Working paper.

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H. Gregersen and C. S. Jensen. Conceptual Modeling of Time-Varying Information. Technical Report TR-35, TimeCenter, 1998.

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H. Gregersen and C. Jensen, "Conceptual Modeling of Time-Varying Information," TIMECENTER Technical Report TR-35, September 10 1998.

....new representational models. Specifically, the objective of this paper is to evaluate the ontological expressiveness of the temporal notational constructs of three selected temporal ER models: the Entity Relation Time (ERT) model [21] the TERC model [26] and the Time Extended ER model (TIMEER) [7]. Each of these temporal ER model extensions is well documented, and together the models represent a substantial range of the designs space for temporal extensions. The evaluation will consider the uses of the models for both analysis and design, and it is evaluated how well the models capture ....

H. Gregersen and C. S. Jensen. Conceptual Modeling of Time-varying Information. Technical Report TR-35, TimeCenter, September 1998.

....of a 7 database object. The versions of entity instances (or their attributes) are referred to as extension versioning and versioning of the definitions of the entities is termed as schema versioning [74] Existence time, which applies to an object, is the valid time when the object exists [25]; it is also referred to as a lifespan [32] of the object. While the temporal granularity can be specified for existence time and valid time, that for transaction time is system defined. The transaction time has duration from insertion to (logical) deletion [34] and can include granules only up to ....

H. Gregersen and C. Jensen, Conceptual Modeling of Time-Varying Information, TIMECENTER Technical Report TR-35, September 10 1998.

....code FROM TEMPORAL ER MODELS TO RELATIONS 1053 and by the database designer to the ER diagrams. For Employee entities, such attributes could record birth dates, hiring dates, etc. One of the temporally extended ER models developed in the research community is the Time Extended ER model, TIMEER [9]. This model extends the ER model with annotations for specifying the temporal aspects that need to be captured in the underlying data base, and it is the only model that explicitly supports lifespans, valid time, and transaction time. For this reason, we have chosen the TIMEER model as input to ....

.... the EER model. The EER model presented by Elmasri and Navathe [7] is chosen as the outset for TIMEER. The reader is assumed to be familiar with that model. The modeling constructs of the TIMEER model are presented next. The TIMEER model, including its formal semantics, is described in detail in [9]. The model has implicit temporal support, but the EER constructs and their semantics are retained, i.e. notation and semantics are added to the EER model to arrive at the TIMEER model. It extends the EER model to better capture, where indicated, temporal aspects of entities, relationships, ....

[Article contains additional citation context not shown here]

H. Gregersen and C. S. Jensen. Conceptual Modeling of Time-varying Information. TIMECENTER Technical Report TR-35, September 1998.

.... Model for Objects with Temporal Attributes and Relationships [32] ER OO Temporal EER model [10, 11] EER Semantic Temporal EER model [8, 9] ER Entity Relation Time model [41, 42, 29] ER Temporal ER model [40] ER Temporal EER model [27] EER Kraft s Model [26] ER TERC [47] ERC TimeER [16] EER Table 1: Overview of Temporal ER Models 6 Summary and Directions In order to exploit the full potential of database technology conventionalas well as temporal guidelines for the design of appropriate database schemas are required. This chapter has presented concepts for capturing the ....

H. Gregersen and C. S. Jensen. Conceptual Modeling of Time-Varying Information. TimeCenter TR-35, Department of Computer Science, Aalborg University (1998).

....but only externally, in the application code and by the database designer to the ER diagrams. For Employee entities, such attributes could record birth dates, hiring dates, etc. One of the temporally extended ER models developed in the research community is the Time Extended ER model, TIMEER [9]. This model extends the ER model with annotations for specifying the temporal aspects that need to be captured in the underlying data base, and it is the only model that explicitly supports lifespans, valid time, and transaction time. For this reason, we have chosen the TIMEER model as input to ....

.... the EER model. The EER model presented by Elmasri and Navathe [7] is chosen as the outset for TIMEER. The reader is assumed to be familiar with that model. The modeling constructs of the TIMEER model are presented next. The TIMEER model, including its formal semantics, is described in detail in [9]. The model has implicit temporal support, but the EER constructs and their semantics are retained, i.e. notation and semantics are added to the EER model to arrive at the TIMEER model. It extends the EER model to better capture, where indicated, temporal aspects of entities, relationships, ....

[Article contains additional citation context not shown here]

H. Gregersen and C. S. Jensen. Conceptual Modeling of Time-varying Information. TIMECENTER Technical Report TR-35, September 1998.

No context found.

Gregersen, H. & Jensen, C. (1998), Conceptual modeling of time-varying information, Technical report, Time Center, TR-35.

No context found.

H. Gregersen and J.S. Jensen. Conceptual modeling of time-varying information. Technical Report TimeCenter TR-35, Aalborg University, Denmark, 1998.

No context found.

H. Gregersen and J.S. Jensen. Conceptual modeling of time-varying information. Technical Report TimeCenter TR-35, Aalborg University, Denmark, 1998.

No context found.

H. Gregersen and C. Jensen. Conceptual Modeling of Time-varying Information, 1998.

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H. Gregersen and C. Jensen. Conceptual modeling of time-varying information, 1998.

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