Inadequacy of interval timestamps in temporal databases

Gadia, Shashi K.; Yeung, Chuen-Sing

doi:10.1016/0020-0255(91)90042-s

Cited by 24 publications

(18 citation statements)

References 6 publications

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“…Interval algebra has successfully applied to multi-agents (Kraus, Wilkenfeld, and Zlotkin 1995), to temporal databases for manipulating their time relationships (Gadia and Yeung 1991;Snodgrass 1987), to speci® cally design for simulations (Tuzhilin 1995) to specify temporal properties of concurrent systems (Barringer, Kuiper, and Pnueli 1984). The major challenge in IA is the propagation of temporal relations.…”

Section: Resultsmentioning

confidence: 99%

“…Presently, it has been taken as a basic framework for temporal reasoning. And this model has also successfully applied to multi-agents (Kraus, Wilkenfeld, and Zlotkin 1995;Shoham and Tennenholtz 1994), to databases for manipulating their time relationships (Snodgrass 1987;Gadia and Yeung 1991;Moeira and Edelweiss 1999), to speci® cally design for simulations (Tuzhilin 1995), and to specify temporal properties of concurrent systems (Barringer, Kuiper, and Pnueli 1984).…”

Section: Related Workmentioning

confidence: 97%

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Propagating temporal relations of intervals by matrix

Zhang¹,

Zhang²

2002

Applied Artificial Intelligence

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Section: Resultsmentioning

confidence: 99%

Section: Related Workmentioning

confidence: 97%

Propagating temporal relations of intervals by matrix

Zhang¹,

Zhang²

2002

Applied Artificial Intelligence

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“…The strongest type of key can be found in Gadia and Yeung [1991] and Gadia and Nair [1993]. Here "a relation r over R, with K ʕ R as its key is a finite set of nonempty [N1NF] tuples such that no key attribute value of a tuple changes with time and no two tuples agree on all their key attributes" [Gadia and Nair 1993].…”

Section: Object Identificationmentioning

confidence: 99%

Temporal FDs on complex objects

Wijsen

1999

ACM Trans. Database Syst.

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Temporal functional dependencies (TFD) are defined for temporal databases that include object identity. It is argued that object identity can overcome certain semantic difficulties with existing temporal relational data models. Practical applications of TFDs in object bases are discussed. Reasoning about TFDs is at the center of this paper. It turns out that the distinction between acyclic and cyclic schemas is significant. For acyclic schemas, a complete axiomatization for finite implication is given and an algorithm for deciding finite implication provided. The same axiomatization is proven complete for unrestricted implication in unrestricted schemas, which can be cyclic. An interesting result is that there are cyclic schemas for which unrestricted and finite implication do not coincide. TFDs relate and extend some earlier work on dependency theory in temporal databases. Throughout this paper, the construct of TFD is compared with the notion of temporal FD introduced by Wang et al. [1997]. A comparison with other related work is provided at the end of the article.

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“…For simplicity, it is assumed that [0,NOW] is the discrete set {0,1,⋅⋅⋅,NOW}. Time intervals are not adequate to model the history of an object in a single tuple, and they lead to query languages that are difficult to use [GY91]. To obtain timestamps that are closed under the set theoretic operations, the concept of temporal elements is introduced.…”

Section: Temporal Elementsmentioning

confidence: 99%

Algebraic identities and query optimization in a parametric model for relational temporal databases

Gadia

Nair²

1998

IEEE Trans. Knowl. Data Eng.

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This paper presents algebraic identities and algebraic query optimization for a parametric model for temporal databases. The parametric model has several features not present in the classical model. In this model a key is explicitly designated with a relation and an operator is available to change the key. The algebra for the parametric model is three-sorted; it includes relational expressions that evaluate to relations, domain expressions that evaluate to time domains, and boolean expressions that evaluate to TRUE or FALSE. The identities in the parametric model are classified as weak identities and strong identities. Weak identities in this model are largely counterparts of the identities in classical relational databases. Rather than establishing weak identities from scratch, a meta inference mechanism, introduced in the paper, allows weak identities to be induced from their classical counterpart. On the other hand, the strong identities will be established from scratch. An algorithm for algebraic optimization to transform a query to an equivalent query that will execute more efficiently is presented. Abstract. This paper presents algebraic identities and algebraic query optimization for a parametric model for temporal databases. The parametric model has several features not present in the classical model. In this model a key is explicitly designated with a relation and an operator is available to change the key. The algebra for the parametric model is three-sorted; it includes relational expressions that evaluate to relations, domain expressions that evaluate to time domains, and boolean expressions that evaluate to TRUE or FALSE. Disciplines Databases and Information Systems | Systems ArchitectureThe identities in the parametric model are classified as weak identities and strong identities. Weak identities in this model are largely counterparts of the identities in classical relational databases. Rather than establishing weak identities from scratch, a meta inference mechanism, introduced in the paper, allows weak identities to be induced from their classical counterpart. On the other hand, the strong identities will be established from scratch. An algorithm for algebraic optimization to transform a query to an equivalent query that will execute more efficiently is presented.

show abstract

Inadequacy of interval timestamps in temporal databases

Cited by 24 publications

References 6 publications

Propagating temporal relations of intervals by matrix

Propagating temporal relations of intervals by matrix

Temporal FDs on complex objects

Algebraic identities and query optimization in a parametric model for relational temporal databases

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