E. Gunter and L. Libkin, OR-SML: A functional database programming language for disjunctive information and its applications, in "LNCS 856: Proceedings of Database and Expert Systems Applications, Athens, September 1994," 641--650.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....in question exactly ful ls the query, and the other estimates the entropy involved in deciding that the attribute satis es a query. Both measures make the strong assumption that a priori all values of the attributes are equally likely. The second approach is suggested by Gunter and Libkin [59] who discuss the same problem from a di erent angle. They are interested not in the kind of queries investgated by Morrissey for which the necessary information is present in the database, but rather in queries that can only be answered by reasoning with the disjunctive information that is ....

Gunter, E. and Libkin, L. (1994) OR-SML: a functional database programming language for disjunctive information and its applications, Proceedings of the 5th International Conference on Database and Expert System Applications, Athens, 641-650.

....it is shown that nesting at intermediate types does not add expressiveness in presence of aggregate functions and certain generic queries. Other results on expressive power are to be found in [34, 36, 35] Our approach can be used for different collections: languages for or sets were studied in [33, 23, 38] and bag languages in [37] As mentioned before, 54] shows that transitive closure, which is efficiently expressible using structural recursion, has a necessarily exponential implementation in complex object algebra [1] 30] show how to encode related database languages in the simply typed ....

E. Gunter and L. Libkin, OR-SML: A functional database programming language for disjunctive information, in "Proceedings of Conference on Database and Expert Systems Applications," Athens, Greece, September 1994.

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E. Gunter and L. Libkin, OR-SML: A functional database programming language for disjunctive information and its applications, in "LNCS 856: Proceedings of Database and Expert Systems Applications, Athens, September 1994," 641--650.

....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 can be represented via orderings on values, e.g. 2, 33, 13, 9] In [6, 19, 22] a general approach to the treatment of partial information in the ....

....sets and or sets, that suggests an encoding of the approximation constructions. We use the encodings and the language or NRL of [22] to show how a number of typical problems can be solved. We also would like to remark that this approach is not purely theoretical. It was used in the system OR SML [12] (which is the Standard ML enhanced with the types of complex objects and or sets and some features of a DBPL) to query independent databases. Using universality properties Because of the space limitations, we consider only mixes and sandwiches. We consider them as type constructors. That is, ....

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E. Gunter and L. Libkin, OR-SML: A functional database programming language for disjunctive information and its applications. 5th International Conference on Database and Expert Systems Applications, 1994, to appear.

....supports incomplete information must provide orderings at all types, as these can not be lifted from base types if powerful primitives like fixpoints are not used. 4. 4 Language implementation The core language for sets and or sets has been implemented as a library of modules in Standard ML, see [GL94] It was useful in several application such as querying incomplete design databases, or querying independent databases to obtain approximate answers. We believe that in the future implementations several changes must be made. For example, an algebraic syntax of or NRL, which is reflected by the ....

E. Gunter and L. Libkin, OR-SML: A functional database programming language for disjunctive information and its applications. In D. Karagiannis, ed., LNCS 856: Proceedings of Conference on Database and Expert Systems Applications, Athens, 1994, Springer Verlag, 1994, pages 841--850.

.... of using and or trees to develop a new object oriented data model with an ad hoc query facility was exploited in [INV91a, INV91b] The query complexity in this model was analyzed in [IMV89] Recently, a functional query language for databases with disjunctions was designed [LW93a] and implemented [GL94]. In these papers two kinds of queries have been distinguished: structural queries ask questions about the data stored in a database, whereas conceptual queries ask questions about the data encoded by the information in a database. To illustrate the difference between the structural and ....

....ask questions about the data stored in a database, whereas conceptual queries ask questions about the data encoded by the information in a database. To illustrate the difference between the structural and conceptual queries, consider the following example of an incomplete design borrowed from [GL94], see figure 1. Theta Theta Theta B B B Theta Theta Theta B B B Theta Theta Theta B B B Theta Theta Theta B B B Theta Theta Theta B B B Theta Theta Theta B B B Theta Theta Theta B B B Phi Phi Phi Phi H H H H A2 B1 B2 x y z ....

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E. Gunter and L. Libkin. OR-SML: A functional database programming language for disjunctive information and its applications. LNCS 856: Proc. DEXA-94, pages 641-650.

....over very large sets of possible worlds, we have to settle for operations with nondeterministic semantics. This is the price to pay for making the language more practical. 4. We briefly discuss the implementation of the operations presented in this paper. It is done as a library in OR SML [7], the system for querying databases with disjunctive information. Let us give a simple example to explain the gist of our approach. With each object, we associate an annotated object that indicates the choices made for each instance of disjunctive information that is relevant to the query. The ....

....iteration scheme apnorm cont and a limited number of auxiliary functions. In this way it is easy to add new variations of normalization primitives. 5 Implementation project The collection of normalization primitives discussed in this paper has been implemented as a library in the system OR SML [7], which itself is a database programming language on top of Standard ML of New Jersey [8] In OR SML, complex objects are SML values, and one can take advantage of combining the features of a query language with the features of a fully fledged programming language. For example, we can use SML ....

E. Gunter and L. Libkin. OR-SML: A functional database programming language for disjunctive information and its applications. Proc. Database and Expert Systems Applications, 1994, Springer LNCS 856, pages 641-650.

....to HOL90. OR SML is also capable of being built as a stand alone system, and as such, has certain features (for example file I O, and the ability to handle multisets) that were not relevant to this setting and were not described here. A more complete description of the full system can be found in [6]. By interfacing HOL90 to a powerful, general purpose, database query language with good theoretical properties, such as a clear semantics, we believe we have provided a good tool for theory browsing as well as a solid platform for future work in constructing theorem proving methodologies that ....

E. Gunter and L. Libkin, OR-SML: A functional database programming language for disjunctive information and its applications, In: D. Karagiannis ed., Proc. 5th Internat. Conf. on Database and Expert Systems Applications (DEXA'94), Athens, Greece, September 1994. Springer-Verlag LNCS vol. 856, 1994, pp. 641--650.

....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 can be represented via orderings on values [3, 16, 12] In A general approach to the treatment of partial information in the context of ordered ....

....of the approximation constructions. We use the encodings and the language or GammaNRA of [25] to show how a number of typical problems can be solved. Encoding approximations in the type system with or sets gives us more than a purely theoretical result. There exists a system called OR SML [15], which is a set of libraries on top of Standard ML that implement the types of complex objects and or sets and some features of a database programming language. We can use the encoding and then program some basic algorithms for querying independent databases in a working systems. Preliminary ....

[Article contains additional citation context not shown here]

E. Gunter and L. Libkin, OR-SML: A functional database programming language for disjunctive information and its applications. 5th Int. Conf. on Database and Expert Systems Applications, LNCS 856, Springer Verlag, 1994, pages 641--650.

....constructs with sets and orsets, the following can be expressed in or NRL. 1. All operations on approximations arising from the universality properties. 2. Orderings on approximations and tests for the consistency conditions. 3. All languages L . 2 This encoding has been used in practice. In [12] it was shown how OR SML, an SML based DBPL whose core language is essentially or NRL can be used to define the promotion operation of [3] which forces a sandwich into a mix using assumptions about keys. It was also shown that a simple change in the program allows to drop the key assumption, ....

E. Gunter and L. Libkin. OR-SML: A functional database programming language for disjunctive information and its applications. LNCS 856: Proc. DEXA-94, pages 641-650.

....as follows from the results of [5] and this paper, are definable in or NRA . Another library defines a lifting of linear orders from base types to arbitrary types which is definable in or NRA as demonstrated in [26] A complete description of this implementation of or NRA can be found in [12]. There are many further problems which we would like to investigate. The use of bags in the proof of the coherence theorem suggests adding or sets to a bag language. We would like to study the language obtained by combining the or set component of or NRA and the standard nested bag language such ....

E. Gunter and L. Libkin, OR-SML: A functional database programming language for disjunctive information and its applications, in "LNCS 856: Proceedings of Database and Expert Systems Applications, Athens, September 1994," 641--650.

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