Re: Joint Committee telecon today 18 February - Outline of RuleML Working Note Draft

From: Harold Boley (
Date: 02/18/03

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    Dear JC Colleagues,
    please find enclosed the current Outline version of the RuleML Working Note
    Draft that Said, Benjamin, and I have been working on in conjunction with
    the RuleML Steering Committee.
    RuleML - Semantic Web Rule Markup Language
    The information presented in this Table of Contents Draft is intended for the
    sole use of the DAML Joint Committee. This is only a preliminary Draft. Expect
    updated versions of the document to be accessible from
    in the future.
    Working Note Draft, 16 February 2003
      Harold Boley ( 
      Benjamin Grosof ( 
      Said Tabet (
    Copyright 2000-2003, The RuleML Initiative.
    This document describes RuleML, the Rule Markup Language. RuleML is a markup 
    language for publishing and sharing rule bases on the World Wide Web. RuleML 
    builds a hierarchy of rule sublanguages upon XML, RDF, XSLT, OWL, and other
    W3C languages.
    Table of Contents
      Abstract and Brief Summary (BG-ST-HB) 
        Goal of interoperable rules over/on the Web to support integration of 
        knowledge bases comprised of rules and facts 
        Design approach based on declarative logic programs 
        Webized to use URI's, namespaces, and XML 
        Encode rulebases in XML or RDF syntax 
        Various expressive extensions done; more possible, some already in progress 
        Synergizes with other aspects of Web standards, especially Semantic Web 
        (RDF, OWL) and Web Services (Web Choreography, DAML-S); anticipated with 
        Semantic Web Services in near future -- to be coordinated with Joint 
      Background (ST-BG-HB) 
        The need for Rules on the Web 
        Earlier work on interoperable Web rules using XML markup 
        The Rule Markup Initiative 
        Rules in the Semantic Web 
        Rules in Web Services 
        Later: Rules in other W3C efforts, e.g., P3P/APPEL, XQuery, XSLT; SWSC) 
        Why standardize rules now 
      RuleML Goals, Requirements, and Design Approach -- to be shortened (BG-ST-HB) 
        Goal of interoperable rules over/on the Web to support integration of 
        knowledge bases comprised of rules and facts 
        Based on underlying KR with well-understood semantics, interoperation with 
        semantic equivalence 
        Initially targeted families of rule systems are currently commercially the 
        most important (later: FOL theorem-prover fragments) 
          Relational DB's, SQL-99 
          ISO Prolog 
          Production rule systems (from OPS5 to Jess) 
          ECA rules 
          OCL (constraint part of UML) 
        Requirements for both forward and backward inferencing 
        Requirements for negation: Negation as failure (NAF), strong negation (NEG), 
        and - most declaratively - NAF-NEG-neutral negation (NOT) 
        Requirements for prioritized conflict handling 
        Design approach: based on declarative logic programs start with Datalog as 
        kernel, then add extensions guided by research/development maturity, 
        practical importance, strategic/evolutionary considerations 
        General objectives 
          Be in spirit of the Web, accomodate its openness, exploit its other 
          aspects: esp. URI's, namespaces, XML as syntactic vehicle 
          Design approach of Webizing: name relations and functions, rules, rule 
          subsets/modules -- by using URI's and namespaces 
          Bridge XML and RDF data models, be able to exploit RDF and harmonize with 
          it (this might help speed RDF in rules world) 
          Tasks: inferencing, (XSLT) translation, static analysis 
          Applications: business policies, business process automation and workflow, 
          e-contracting, security/authorization/trust 
        Aim to support RDF, and also to support XML directly for those not 
        (directly) dealing with RDF 
        Design approach: abstract (graph-theoretical) data model with labeled arcs 
        and minimal ordered arcs; inspired by software/data engineering practice, 
        and by RDF, alternative syntactic encodings in XML and RDF; in-progress also 
        in OWL -- to be coordinated with Joint Committee 
        Pursue: multiple KR expressiveness classes, which form a partial order 
        Design approach: hierarchy of expressive classes, syntax specification 
        (incl. DTDs and later XML Schema) for each 
          Some defined already, others in progress, even more ones provided from 
          RuleML community 
          Need syntactic mechanics for this: e.g., in DTDs and XML Schema 
          In progress: it's useful to think in terms of a few different rules types: 
          not just derivation and transformation, but also: action/reaction; 
          however, these not yet well worked out wrt consensus way to view them, nor 
          in some ways wrt the fundamental research understanding 
      Language Structure (HB-ST-BG) 
        Rule Types: Derivation, Transformation, and (in progress) Reaction 
        Webized Logic: URIrefs for constants, relations, and functions 
        The Hierarchy of expressive classes 
          Example: diamond formed by Datalog, Horn, Datalog+NAF, Horn+NAF 
          Overview of some others: UR versions + RDF versions 
        Plugging in Different Sets of Relational and Functional Built-ins (ISO 
        Prolog, CommonRules, CommonLogic/KIF, Jess, etc.) 
      The Kernel Datalog Sublanguage (HB-BG-ST) 
        Datalog Facts 
        Datalog Rules 
      The Full Horn Sublanguage (HB) 
        Complex Terms 
        Later: List Terms as a special case 
      The Transformational Sublanguage (HB) 
        Function calls via nano elements 
        Call-by-value nestings 
        Function definitions through trans elements 
      Negation as Failure (NAF), Normal Logic Programs -- to be udated (BG-HB-ST) 
        English explanation: What it does, relationships to NEG and NOT 
        Explain the need: For W3C, IR, rules, and database communities 
        Explain the restriction: Failure Negation appearing only on selected body 
        Allowed uses of NAF and conjunctions in the body 
      The Prioritized Sublanguage (BG-ST-HB) 
        Rule labels 
        Partial order for rule prioritization 
        Later: Certainty factors and their transformation into a partial order 
      The Object-Centered Sublanguage (HB-ST-BG) 
        Concept; a metarole for user-defined role names; relationship to OO 
        Relationships to positionalized sublanguages 
        Modeling RDF resources and OWL instances -- to be coordinated with Joint 
        Later: Modeling instances of F-Logic and Case-based reasoning 
        Later: Types and inheritance as in OWL classes and Description LP -- to be 
        coordinated with Joint Committee 
      Lloyd-Topor Logic Programs: More First-Order Logic Features (BG-ST-HB) 
        Lloyd-Topor Transformation without, then with NAF 
        Disjunction and conjunction in body 
        Conjunction in head 
        Later: Existentials in body 
        Later: Universals in head 
        Later: Universals in body 
        Later: Negation 
      Rulebases, Queries, and Turnstiles (HB-BG) 
        The rulebase element for expressing and transmitting assertions 
        The query element for expressing and transmitting queries 
        The turnstile element for posing a query to a rulebase 
        Relationships to DAML Query, RDF Query, and XML Query 
      Local Modules and Global Inclusions (ST-BG-HB) 
        Modules: Using turnstile elements in rule bodies 
        Inclusions: Loading external rulebases 
      Reaction Rules (cf. "V1 Draft" of Reaction Rules Subgroup) 
        Notion of Event 
        Notion of Condition (from Derivation Rules) 
        Notion of Action 
        Notion of Postcondition (for declarative state change) 
        Event-Condition-Action-Postcondition (ECAP) Rules 
      Reference Implementations (HB-BG-ST) 
        Concepts: translation, querying and inferencing, authoring, application 
        XSLT Translators 
          Translators between sublanguages 
          Translators to other languages 
          Translators to (X)HTML for customized human-oriented renderings 
        Query and Inference Engines 
        Graphical Editors 
        RuleML-based Applications 
      Use Cases / RuleML-Based Applications (ST-BG-HB) 
        Another document in progress, i.e., from Joint Committee 
        Animals Rulebase 
        Supply Chain e-Contracting 
        Rental car business rules 
        Book Pricing 
      Appendices (BG-ST-HB) 
        Appendix A. The RDF-XML-Integrating Data Model for the Abstract Syntax: 
        Types and Roles (HB) 
        Appendix B. The Hierarchy of DTDs with Specs for all Sublanguages (HB-ST-BG) 
          Abstract Syntax 
          Associated Semantics 
          Complete DTDs / XML Schemas 
          RDF Syntax 
          Later: N3 Syntax 
        Appendix C. The Standard Built-Ins Based on XML Schema, Part II, Datatypes 
        Appendix D. Notes (HB-BG-ST) 
        Appendix E. Index of All Language Elements (HB-BG-ST)

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