LOLA(ID:3564/lol002)

For LOgic LAnguage

Burkhard Freitag Munich University 1991

Runtime Language for Deductive Databases

Structures:
References:
  • Bayer, Rudolf MOOD: A Knowledgebase System with Objectoriented Deduction. DASFAA 1991: 320-329 view details
  • Burkhard Freitag: Module und Hypothetisches Schließen in Deduktiven Datenbanken. Dissertation, TU München, 1991 view details
  • Freitag, Burkhard; Schütz, Heribert; Specht, Günther "LOLA - A Logic Language for Deductive Databases and its Implementation" view details
          in DASFAA 1991 view details
  • Burkhard Freitag, Heribert Schütz, Günther Specht, Rudolf Bayer, Ulrich Güntzer: LOLA - ein deduktives Datenbanksystem. Objektbanken für Experten 1992: 1-28 view details
          in DASFAA 1991 view details
  • Burkhard Freitag: Extending Deductive Database Languages by Embedded Implications view details
          in LPAR 1992 view details
  • Specht, Günther; Freitag, Burkhard; Schütz, Heribert "AMOS: A Natural Language Parser written in LOLA" pp124-133 view details
          in Workshop on Programming with Logic Databases (Informal Proceedings), ILPS 1993 view details
  • Specht, Günther Source-to-Source Transformationen zur Erklärung des Programmverhaltens bei deduktiven Datenbanken. DISKI Vol. 42 Infix Verlag, St. Augustin, Germany 1993, ISBN 3-929037-42-4 view details
          in Workshop on Programming with Logic Databases (Informal Proceedings), ILPS 1993 view details
  • Zukowski, Ulrich ; Burkhard Freitag: Adding Flexibility to Query Evaluation for Modularly Stratified Databases. JICSLP 1996: 304-318 1993 view details
          in Workshop on Programming with Logic Databases (Informal Proceedings), ILPS 1993 view details
  • Zukowski, Ulrich ; Burkhard Freitag, Stefan Brass: Improving the Alternating Fixpoint: The Transformation Approach. LPNMR 1997: 4-59 Carl-Alexander Wichert, Burkhard Freitag: Capturing Database Dynamics by Deferred Updates. ICLP 1997: 226-240 1996 view details
          in Workshop on Programming with Logic Databases (Informal Proceedings), ILPS 1993 view details
  • Zukowski, Ulrich; Freitag, Burkhard "The Deductive Database System LOLA" view details Abstract: Abstract:
    The LOLA system has been designed as the query answering component of a deductive database system and integrates ideas from logic programming and relational query processing. LOLA is based on a clausal logic programming language with function symbols, negation, grouping and aggregation, special predicates for accessing multiple external relational databases, and user-definable computed predicates.
    Query processing has two phases: In the compilation phase a query against a program is translated into an evaluating expression thereby proceeding top-down from the query to the base relations or user-defined predicates. In the evaluation phase, the resulting expression computes the set of answer tuples corresponding to the query and the current extensional database. Extensional relations can reside in main memory or in any external relational database system accessible via SQL. The basic evaluation scheme is set-oriented, bottom-up based on semi-naive fixpoint iteration, but a closer look reveals that query processing in LOLA consists of a demand-driven and a data-driven part. For simple programs, this can be achieved by applying a form of the magic set transformation and using the core bottom-up engine to evaluate the transformed program. However, it is well-known that the magic set transformation does not harmonize with negation. As will be described in this paper, the LOLA compiler splits the program into partitions that can be safely magic set transformed and processed bottom-up whereas the communication between the partitions is compiled into function calls that realize top-down control. This technique is correct for modularly stratified negation (w.r.t.\ the well-founded semantics) and group-stratified aggregation. Current work addresses generalizations of the currently implemented approach that are suitable to evaluate general logic programs.

          in LPNMR 1997 view details
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