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Last modified: November 27, 2000
Relational-Functional Markup Language (RFML)

[July 28, 2000] "The Relational-Functional Markup Language (RFML) is an XML application for Relfun-style declarative programming and knowledge representation. RFML has been implemented as a (Web-)output syntax for relational-functional knowledge bases and computations. It is part of the Relfun system."


  • RFML Home Page

  • Document Type Definition (DTD). 2000-04-29 or later. [cache]

  • Draft Specification

  • "Markup Languages for Functional-Logic Programming." By Harold Boley (Deutsches Forschungszentrum fuer Kuenstliche Intelligenz GmbH, Germany).

  • [November 27, 2000] "Markup Languages for Functional-Logic Programming." By Harold Boley (Deutsches Forschungszentrum für Künstliche Intelligenz GmbH). Paper presented at WFLP'2000 - Ninth International Workshop on Functional and Logic Programming, Benicassim (Spain), September 28-30, 2000. "A ten-step strategy for sharing integrated functional-logic programs or knowledge bases as XML documents is given. Four well-known functional-logic design essentials are revisited for the Web. An XML-based 'vanilla' Prolog (XmlLog) is defined and developed into the Relational-Functional Markup Language (RFML). 'Content markup' in MathML is regarded as a (higher-order) sublanguage for Lisp-like notations in XML and is compared to RFML. XML assertion and query languages are unified in this functional-logic setting. XmlLog and subsets of RFML are specified by XML document type definitions. All notions are illustrated with examples, culminating in binary-tree relabeling... [Purely Relational Markup in XmlLog and RFML:] XmlLog is a 'vanilla' markup language for purely relational specifications in XML [Bol00], realizing the non-groundness/non-determinism essentials (R1) and (R2) from section 2 above. Here we discuss its (essentially, specialization) kinship with RFML. An individual (or variable or predicate) in XmlLog becomes an ind (or var or relator) element of the form <ind> . . . </ind> (or analogous). A relationship element applying a relator to ind/var arguments is usable as a query. In XmlLog a relationship becomes a Datalog (i.e., constructorless) fact through a superimposed hn (i.e., Horn-clause) element. Let us consider a fact corresponding to the tuple (eurostar,fred) from a carry(Carrier,Person) table of a relational database: carry(eurostar,fred). It is marked up in XmlLog as follows [...] More generally, a Datalog rule in XmlLog is asserted as an hn element that displays two or more subelements, namely, the head-relationship element followed by at least one body-relationship element... Our XmlLog markup for Datalog can be extended to full Prolog and formalized as follows. A Horn clause hn has one (fact) or more (rule) relationship subelements. A relationship element applies a relator to zero or more arguments that can now also be structures. A struc element applies a constructor to arguments identical to those of relator applications. The DTD for XmlLog, then, just consists of these ELEMENT declarations for a knowledge base kb of zero or more hn clauses... The first well-known language that has provided Horn-clause markup in the Web is SHOE (Simple HTML Ontology Extensions). XmlLog defines a 'vanilla' Horn language as an XML DTD, extended to RFML, a 'lightweight' FL-integration language. RFML has been implemented as a (Web-)output syntax for FL knowledge bases and for FL computations. This FL/XML kernel could be extended for further FL languages. It will be a problem, of course, to share programs between the large number of FL proposals [...] As one approach, we could develop a merely syntactic common markup language as done by the MathML community (who, however, have the advantage of the generally agreed upon semantics of mathematical expressions); experience with different semantics for the same markup might then encourage semantic convergence... Much of the knowledge on the Web constitutes definitions of relations and functions. Markup languages for FL programming will permit such 'Functional-Logic Knowledge on the Web'. Their development should take into account previous experience such as with the Knowledge Interchange Format (KIF), which can also be regarded as an FL language. KIF is a full rst-order logic language that has been proposed as an ANSI standard. However, full KIF currently seems still too big for practical knowledge sharing. For example, only a (Horn-like) subset of KIF has been employed in the recent Business Rules Markup Language (BRML). Thus, a complementary approach has been pursued with Relfun/RFML: gradually extending a minimal kernel towards a practical FL language." [cache]

  • [July 28, 2000] "Knowledge Markup Techniques Tutorial." By Harold Boley, Stefan Decker, and Michael Sintek. Paper to be presented at ECAI 2000/PAIS 2000 (14th European Conference on Artificial Intelligence Prestigious Applications of Intelligent Systems, Berlin, Humboldt University, August 20-25, 2000). "There is an increasing demand for formalized knowledge on the Web. Several communities (e.g., in bioinformatics and educational media) are getting ready to offer semiformal or formal Web content. XML-based markup languages provide a 'universal' storage and interchange format for such Web-distributed knowledge representation. This tutorial introduces techniques for knowledge markup: we show how to map AI representations (e.g., logics and frames) to XML (incl. RDF and RDF Schema), discuss how to specify XML DTDs and RDF (Schema) descriptions for various representations, survey existing XML extensions for knowledge bases/ontologies, deal with the acquisition and processing of such representations, and detail selected applications. After the tutorial, participants will have absorbed the theoretical foundation and practical use of knowledge markup and will be able to assess XML applications and extensions for AI. Besides bringing to bear existing AI techniques for a Web-based knowledge markup scenario, the tutorial will identify new AI research directions for further developing this scenario. [Harold Boley has reinterpreted markup techniques for knowledge representation, showing the use of functional-logic programming in/for the Web, mapping the knowledge model of Protégé to XML-based systems, and developing the Relational-Functional Markup Language (RFML). Stefan Decker has worked in IT support for knowledge management using knowledge markup techniques facilitated by ontology, metadata and knowledge representation based approaches; he is currently working on scalable knowledge composition methods. Michael Sintek developed an XML import/export extension of the frame-based knowledge acquisition and modeling tool Protégé-2000 and currently works on XML/RDF-based methods and tools for building organizational memories in the DFKI FRODO project.]"

  • Contact: Harold Boley

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