Dyreson, C. E. and Snodgrass, R. (1993). Historical Indeterminacy. In IEEE International Conference on Data Engineering.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....= equalities any practical temporal domain crucially depends on the number of temporal dimensions: PTIME for one dimension, co NP complete for more than one dimension. ner approacnes Temporal databases: point and interval relationships [Chaudhuri, 1988] quantitative indeterminacy [Dyreson and Snodgrass, 1993] lower and upper bounds on an interval [Gadia et al. 1992] Artificial intelligence: 13 basic kinds of relationships between intervals, algebra of relationships [Allen, 1983] disjunctive information metric information [Meiri, 1991] Kautz and Ladkin, 1991] Example: I1 before, after I2 ....

Dyreson, C. E. and Snodgrass, R. (1993). Historical Indeterminacy. In IEEE International Conference on Data Engineering.

....be made constructive [120] ffl co NP complete for n dimensional time (n 2) 119] has also many very interesting results about the combined complexity of evaluating queries that we can not discuss here because of the lack of space. The results of [119] apply to Z, Q, as well as finite orders. [38, 53, 52] pursued the problem of incomplete temporal information for concrete query languages. They didn t base their approaches on [57] but to some degree their approaches can be recast using the framework of [76] In the context of the discrete temporal domain Z, 38] postulated to represent an ....

....Q, as well as finite orders. 38, 53, 52] pursued the problem of incomplete temporal information for concrete query languages. They didn t base their approaches on [57] but to some degree their approaches can be recast using the framework of [76] In the context of the discrete temporal domain Z, [38] postulated to represent an indefinite point by a possible interval , which could be viewed as an indefinite timestamp formula (e.g. t = c 0 c 5 meaning some instant between 0 and 5 ) and an indefinite interval by a pair of possible intervals. Null values appearing in timestamp formulas ....

[Article contains additional citation context not shown here]

C. E. Dyreson and R.T. Snodgrass. Historical Indeterminacy. In IEEE International Conference on Data Engineering, 1993.

....) co NP complete for more than one dimension. BRICS Mini course on Temporal Databases The qualitative part of these can be recast using Koubarakis approach. 103 2 Other approaches Temporal databases: ffl point and interval relationships [Chaudhuri, 1988] ffl quantitative indeterminacy [Dyreson and Snodgrass, 1993] ffl lower and upper bounds on an interval [Gadia et al. 1992] Artificial intelligence: ffl 13 basic kinds of relationships between intervals, algebra of relationships [Allen, 1983] ffl disjunctive information ffl metric information [Meiri, 1991] Kautz and Ladkin, 1991] Example: I 1 ....

Dyreson, C. E. and Snodgrass, R. (1993). Historical Indeterminacy. In IEEE International Conference on Data Engineering.

....events are determinate. In reality, events may not be known to such a fine precision. For example, we may know that Ed and Alice were married in September 1955, but we may not know the precise day (or even second) when the ceremony occurred. Work is currently under way to eliminate this assumption [Dyreson Snodgrass 1992]. Specification of event values is done with a string like notation. An event constant is syntactically delimited by vertical bars ( 1 The string of characters contained within the bars is interpreted as an event constant by a calendar. 2 A single vertical bar within an event constant ....

....the concept of null values. A null in SQL is used to represent indeterminacy, i.e. that an attribute has no applicable value or that a value exists but is unknown [Date 1989A] In general, temporal data can exhibit both two kinds of indeterminacy, value indeterminacy and historical indeterminacy [Dyreson Snodgrass 1992]. Value indeterminacy covers the two types of indeterminacy denoted by null and mentioned above. Temporal indeterminacy deals with the uncertainty of when occurrences happened in time. SQL support for temporal indeterminacy is being investigated separately and will not be addressed here. This ....

[Article contains additional citation context not shown here]

Dyreson, C. E. and R. T. Snodgrass. "Historical Indeterminacy." Technical Report TR 91-30a. Computer Science Department, University of Arizona. Revised Feb. 1992.

....the meaning of all extant TQuel retrieve statements. 5.1 Syntactic Extensions for Valid time Indeterminacy We make two syntactic extensions to TQuel s retrieve statement, one to specify the range credibility and the other to specify the ordering plausibility. Details are presented elsewhere [Dyreson Snodgrass 1992A] Range credibility appears (optionally) in the range statement of an interval relation. The credibility applies independently to the starting and terminating events in the interval. It can be any integer value between 0 and 100 (inclusive) The credibility phrase has an initial default value of ....

....overlap in indeterminate valid time. The tuples produced by the retrieve statement are coalesced by the Reduce function. A new function Reduce 0 computes the minimal set of value equivalent indeterminate tuples, i.e. the set for which there are no such tuples. Details are presented elsewhere [Dyreson Snodgrass 1992A] 5.7 Semantics of the Example Query At this point, the semantics of the retrieve statement have been specified. As an example, we trace the computation of the query given in Figure 4 on the database given in Figure 1. The query will result in three tuples, also shown in Figure 4. First, the ....

[Article contains additional citation context not shown here]

Dyreson, C. E. and R. T. Snodgrass. "Historical Indeterminacy." Technical Report TR 91-30a. Computer Science Department, University of Arizona. Revised Feb. 1992.

No context found.

Dyreson, C. E. and R. T. Snodgrass. "Historical Indeterminacy." Technical Report TR 91-30a. Computer Science Department, University of Arizona. Revised Feb. 1992.

Online articles have much greater impact   More about CiteSeer.IST   Add search form to your site   Submit documents   Feedback  

CiteSeer.IST - Copyright Penn State and NEC