B. Rounds. Situation-theoretic aspects of databases. In Proceedings of Conference on Situation Theory and Applications, CSLI vol. 26, 1991, pages 229-256.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....of approximations obtained in section 4. We discuss problems with using this approach, such as undecidability of certain preconditions that need to be checked to ensure well definedness of programs. As a solution to this problem, we suggest an encoding of approximation constructs with or sets [14, 15, 22, 31] and explain how the language for or sets from [22] is suitable for programming with approximations. In fact, a system based on this language [12] has been used in the problems of querying independent databases. 2 Preliminaries Partial objects and ordered sets Most models of partiality of data ....

B. Rounds, Situation-theoretic aspects of databases, In Proceedings of Conference on Situation Theory and Applications, CSLI vol. 26, 1991, pages 229-256.

....the form of disjunctive information. In this paper we describe a functional language, OR SML, for querying databases with incomplete and disjunctive information. To handle disjunctive information, we allow a new type constructor of or sets (hence the name OR SML) Or sets have been studied in [13, 17, 23]. The original motivation for or sets came from applications within design, planning, and scheduling areas. Or sets are in essence disjunctive information, but they are distinguished from the latter by having two distinct interpretations. An or set can either be treated at a structural level or at ....

B. Rounds, Situation-theoretic aspects of databases, In Proc. Conf. on Situation Theory and Applications, CSLI vol. 26, 1991, pages 229--256.

....the form of disjunctive information. In this paper we describe a functional language, OR SML, for querying databases with incomplete and disjunctive information. To handle disjunctive information, we allow a new type constructor of or sets (hence the name OR SML) Or sets have been studied in [14, 18, 24]. The original motivation for or sets came from applications within design, planning, and scheduling areas. Or sets are in essence disjunctive information, but they are distinguished from the latter by having two distinct interpretations. An or set can either be treated at a structural level or at ....

B. Rounds, Situation-theoretic aspects of databases, In Proc. Conf. on Situation Theory and Applications, CSLI vol. 26, 1991, pages 229--256.

....information. It is capable of solving a number of problems that typically accompany disjunctive information; in particular, the problems we discussed above. To handle disjunctive information, we allow a new type constructor of or sets (hence the name OR SML) Or sets have been studied in [8, 10, 14]. Or sets are in essence disjunctive information, but they are distinguished from the latter by having two distinct interpretations. The structural level concerns the precise way in which an or set is constructed. The conceptual level sees an or set as representing an object which is equal to some ....

B. Rounds, Situation-theoretic aspects of databases, In Proc. Conf. on Situation Theory and Applications, CSLI vol. 26, 1991, pages 229--256.

....hold when subsets are restricted to antichains and updates are modified in such a way that after each update only maximal (most informative) elements are retained. 2 We should remark that the Smyth ordering S corresponds to or sets that are sets of possible choices. This was first observed in [14] and formalized in a way similar to Proposition 2.1 in [9] It should also be noted that in early work on using orderings for partiality, orderings for collections were usually chosen in an ad hoc way, without any justification. 2 Ordering Bags of Incomplete Objects We now use similar ....

B. Rounds. Situation-theoretic aspects of databases. In Proceedings of Conference on Situation Theory and Applications, CSLI vol. 26, 1991, pages 229-256.

....designs. For example, how many completed designs are there and is there a completed design that costs under 100 and has reliability at least 95 are examples of conceptual queries. To distinguish ordinary sets from collections of disjunctive possibilities, we call the latter or sets, see [INV91a, LW93a, Rou91]. We use hi to denote orsets. In the example in figure 1, the whole design can be represented as a set fA; Bg, while A is an or set hA1; A2i and B2 is an or set hw; ki. Note that or sets have two distinct representations. With respect to structural queries, or sets behave like sets, but with ....

....languages in which conceptual queries can be formulated. It also has led to development of a prototype [GL94] However, there are several theoretical problems that must be addressed in order to develop practical methods for answering conceptual queries. ffl Only sets have been considered in [INV91a, INV91b, LW93a, Rou91], but many practical languages are based on bags (multisets) In the past few years several approaches to design of bag languages have been proposed. Moreover, most approaches agree on what constitutes the basic set of bag operations [Alb91, GM93, LW93b, LW94] Thus, we believe the normalization ....

B. Rounds, Situation-theoretic aspects of databases, In Proc. Conf. on Situation Theory and Applications, CSLI vol. 26, 1991, pages 229-256.

....and f . Also, they will be labeled by T because they will no longer be pointing at the last element. To formalize this intuitive notion of annotation, we need a formal way of distinguishing instances of disjunctive information. Our approach to representation of disjunctive information is based on [9, 12, 15]: to distinguish ordinary sets from collections of disjunctive possibilities, we call the latter or sets and use hi to Database Programming Languages, 1995 3 Query Language Primitives for Programming with Incomplete Databases denote them. In the design example, A1 can be represented as a set or ....

B. Rounds, Situation-theoretic aspects of databases, In Proc. Conf. on Situation Theory and Applications, CSLI vol. 26, 1991, pages 229-256.

....obtained in section 4 and discuss problems with using this approach. One problem is the undecidability of certain preconditions that need to be checked to ensure well definedness of programs. As a solution to this problem, we suggest an encoding of approximation constructs with or sets [17, 25, 33] and explain how the language for or sets [25] is suitable for programming with approximations. In fact, a system based on this language [15] has been used in the problems of querying independent databases. 2 Preliminaries 2.1 Partial objects and ordered sets Most models of partiality of data ....

....work and recent work [10, 11] on approximating recursive datalog programs with nonrecursive ones. Second, we have shown that some modal operations are naturally associated with approximations. Modal operations have been used in the context of incomplete information in databases, for example, by [25, 33] to describe conjunctive and disjunctive sets by means of modal connectives, and in [20] to provide semantics of constraints. Whether there are any connections between [20, 33] and our work, remains to be seen. Acknowledgements. I wish to thank Peter Buneman, Carl Gunter, Elsa Gunter, Achim Jung, ....

[Article contains additional citation context not shown here]

B. Rounds, Situation-theoretic aspects of databases, In Proceedings of Conference on Situation Theory and Applications, CSLI vol. 26, 1991, pages 229-256.

....and Wong [20] gave an update semantics for the ordering whose meaning is being more informative. The lower powerdomain corresponded to the natural ordering of sets, while the upper powerdomain led to the ordering of so called or sets which in essence are sets of disjunctive possibilities (cf. [15, 31]) However, in some cases it is desirable to retain information conveyed by both upper and lower powerdomains. This happens if the set of partial descriptions is not given explicitly, but rather approximated from below and above. Then one of the approximations, that correspond to the definite ....

B. Rounds, Situation-theoretic aspects of databases, In Proceedings of Conference on Situation Theory and Applications, CSLI vol. 26, 1991, pages 229-256.

....they studied some intrinsic lower bounds on complexity of LDL style [27] queries on or sets. The language can express queries of hyper exponential complexity. Nevertheless, they were successful in identifying certain restricted tractable fragments that are useful in real life applications. Rounds [29] studied complex object databases from the situation theoretic point of view. Connections with natural language problems motivated him to introduce the notions of conjunctive and disjunctive information which correspond exactly to our notions of sets and or sets. He studied order relations on ....

....contributions and organization of this report are summarized below. A query language or NRA that cleanly integrates or sets and more traditional types of data at the structural level is proposed in section 2. In Section 3 we give two semantic representations which are in the spirit of Rounds work [29] but using simpler machinery. For example, using our representations we were able to provide a simple proof that ff s is the isomorphism of semantic domains of types fhsig and hfsgi. A query at the conceptual level is exactly a query on an object that is in a certain normal form. In section 4, ....

[Article contains additional citation context not shown here]

B. Rounds, Situation-theoretic aspects of databases, In Proc. Conf. on Situation Theory and Applications, CSLI vol. 26, 1991, pages 229-256.

....the form of disjunctive information. In this paper we describe a functional language, OR SML, for querying databases with incomplete and disjunctive information. To handle disjunctive information, we allow a new type constructor of orsets (hence the name OR SML) Or sets have been studied in [15, 18, 24]. The original motivation for or sets came from applications within design, planning, and scheduling areas. Or sets are in essence disjunctive information, but they are distinguished from the latter by having two distinct interpretations. An or set can either be treated at a structural level or at ....

B. Rounds, Situation-theoretic aspects of databases, In Proc. Conf. on Situation Theory and Applications, CSLI vol. 26, 1991, pages 229--256.

....they studied some intrinsic lower bounds on complexity of LDL style [29] queries on orsets. The language can express queries of hyper exponential complexity. Nevertheless, they were successful in identifying certain restricted tractable fragments that are useful in real life applications. Rounds [32] studied complex object databases from the situation theoretic point of view. Connections with natural language problems motivated him to introduce the notions of conjunctive and disjunctive information which correspond exactly to our notions of sets and or sets. He studied order relations on ....

....complex objects and their logical representations. Organization. A query language or NRA that cleanly integrates or sets and more traditional types of data at the structural level is proposed in Section 2. In Section 3 we give two semantic representations which are in the spirit of Rounds work [32] but use simpler machinery. For example, using our representations we were able to provide a simple proof that ff s is the isomorphism of semantic domains of types fhsig and hfsgi. A query at the conceptual level is a query on an object that is in a certain normal form. In Section 4, the normal ....

[Article contains additional citation context not shown here]

B. Rounds, Situation-theoretic aspects of databases, in "CSLI 26: Proceedings of 1991 Conference on Situation Theory and Applications," 229-256.

....hold when subsets are restricted to antichains, and updates are modified in such a way that after each update only maximal (most informative) elements are retained. 2 We should remark that the Smyth ordering S corresponds to or sets which are sets of possible choices. This was first observed in [13] and formalized in a way similar to Proposition 2.1 in [8] It should also be noted that in early work on using orderings for partiality, orderings for collections were usually chosen in an ad hoc way, without any justification. Ordering Multisets of Incomplete Objects We now use similar ....

B. Rounds. Situation-theoretic aspects of databases. In Proceedings of Conference on Situation Theory and Applications, CSLI vol. 26, 1991, pages 229-256.

....they studied some intrinsic lower bounds on complexity of LDL style [19] queries on or sets. The language can express queries of hyper exponential complexity. Nevertheless, they were successful in identifying certain restricted tractable fragments that are useful in real life applications. Rounds [20] studied complex object databases from the situation theoretic point of view. Connections with natural language problems motivated him to introduce the notions of conjunctive and disjunctive information which correspond exactly to our notions of sets and or sets. He studied order relations on ....

....contributions and organization of this report are summarized below. A query language or NRA that cleanly integrates or sets and more traditional types of data at the structural level is proposed in section 2. We have also given two semantic representations which are in the spirit of Rounds work [20] but using simpler machinery. For example, using our representations we were able to provide a simple proof that ff s is the isomorphism of semantic domains of types fhsig and hfsgi. A query at the conceptual level is exactly a query on an object that is in a certain normal form. In section 3, ....

[Article contains additional citation context not shown here]

B. Rounds, Situation-theoretic aspects of databases, In Proc. Conf. on Situation Theory and Applications, CSLI vol. 26, 1991, pages 229-256.

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B. Rounds. Situation-theoretic aspects of databases. In Proceedings of Conference on Situation Theory and Applications, CSLI vol. 26, 1991, pages 229-256.

No context found.

B. Rounds, Situation-theoretic aspects of databases, in "CSLI 26: Proceedings of 1991 Conference on Situation Theory and Applications," 229-256.

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