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Accessing Relational and Higher Databases through Database Set Predicates in Logic Programming Langu
| Content Provider | Semantic Scholar |
|---|---|
| Author | Draxler, Christoph |
| Copyright Year | 1991 |
| Abstract | Coupled systems combine the high expressive power of logic programming languages with the efficient storage and administration of large amounts of data in database management systems. Coupled systems are a basic technology for the development of expert database systems. For the implementation of coupled systems the following problems have to be solved: The different evaluation mechanisms implemented in the database management and the logic programming system respectively have to be coordinated on the system architecture level. On the system language level the database access has to be incorporated into the logic programming language in such a way that the full expressive power of the database query language is available. Previous approaches to coupled systems have primarily tried to integrate a database system into the logic language system. In this thesis, I propose instead to embed database access into a logic programming language. This embedding is achieved through database set predicates . Database set predicates extend the set predicates as they are known in current logic programming languages with access to external databases. Database set predicates are predicates of the form db_set_predicate(ProjectionTerm,DatabaseGoal,ResultRelation) ProjectionTerm is a term, and DatabaseGoal is a – possibly complex – database goal formulated in the syntax of the logic programming language. ProjectionTerm and DatabaseGoal are translated to a database query. The query is evaluated in the database system, and the result is returned to the logic programming language where it is held in the standard datastructure ResultRelation . Both ProjectionTerm and DatabaseGoal can be constructed at runtime. This allows a dynamic definition of database access to result in maximally restrictive queries which reduce the amount of data to be imported from the database system. The use of a standard datastructure allows the built-in memory management to be used, which also contributes to the overall efficiency of the approach. An important feature of database set predicates, as compared to other approaches, is the high expressive power of its database access language. Access to higher database systems, e.g. databases with tuple-, listor set-valued attributes, or even nested relations in NF 2 databases, and higher-order control, e.g. sorting or grouping is expressible. Other approaches to coupled systems do not support access to higher databases, and higher-order control has to be programmed explicitly. Database set predicates will be implemented in the application program DedChem . DedChem is a coupled system for synthesis planning in organic chemistry based on name reactions. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.phonetik.uni-muenchen.de/institut/mitarbeiter/draxler/DraxlThs.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
