CmpE 583- Web Semantics: Theory and Practice RULES & RULE MARKUP Atilla ELÇİ Computer Engineering Department Eastern Mediterranean University 17.12.04 updated 28.12.06 CmpE 583 Fall 2008

Introduction Rules serve to: On top of ontologies layer there rests rules layer in the semantic Web protocol stack. Rules are of differing nature / purpose (the rule spectrum): Derivation rules Transformation rules Reaction rules Rules serve to: Specify queries and inferences in Web ontologies, Mappings between Web ontologies, and Dynamic Web behaviors of workflows, services, and agents. Rules can be stated in natural language, some formal notation, or in a combination of both. 17.12.04 updated 28.12.06 CmpE 583 Fall 2008

Agenda Rules & facts RuleML (Rule Markup Language) Ontology rule languages like the Semantic Web Rule Language (SWRL), which combine RuleML with OWL. Rule Interchange Format initiative at W3C. 17.12.04 Rev. 11.01.2009 CmpE 583 Fall 2008

Rules & Facts [TBL-1998] The Semantic Web is a universal space for anything which can be expressed in classical logic. (NB: try reverse this sentence; implication is: anything of classical logic is in the Semantic web!). Many knowledge representation systems exist. All distinguish data and rules: Data: pool of info; expressed in a simple language (NB: but not in a natural language). Rules: Control the inference steps Written in a restricted language (NB: so to maintain computability) Aim at preserving computability. Conveys two separate pieces of info: Classic logic fact (NB: as embedded in the rule system) Deduced-implied finding (NB: that is, append all rules as extracted from fact documentation and their implication). The Semantic Web uses the classical logic. Inconsistent data is tolerated because trust is based on verified reputation of the source. (NB: Every document has its “truth” system; user consumes that whose creator/conveyor he/she knows as reputable and trusts). 17.12.04 updated 28.12.06 CmpE 583 Fall 2008

RuleML docs [RuleML Homesite] Rules can be stated in natural language, in some formal notation, or in a combination of both. Being in the 'semiformal' category, the RuleML Initiative is working towards an XML-based markup language that permits Web-based rule storage, interchange, retrieval, and firing/application. RuleML covers the entire rule spectrum, from derivation rules to transformation rules to reaction rules. RuleML can thus specify queries and inferences in Web ontologies, mappings between Web ontologies, and dynamic Web behaviors of workflows, services, and agents. Aiming for business intelligence, AI? Harold Boley: RuleML Initial Steps, Version 1.0. 2002-08-22. Harold Boley, Benjamin Grosof, Michael Sintek, Said Tabet, Gerd Wagner: RuleML Design, Version 0.8. 2002-09-03. 17.12.04 updated 28.12.06 CmpE 583 Fall 2008

RuleML presentations By Benjamin N. Grosof and Harold Boley: "Introduction to RuleML", slides of teleconference talk (in pdf). "Part 2 of 2: Additional Optional Slides" (in pdf). "RuleML Intro Examples and More Syntax Details". The RuleML Tutorial. 17.12.04 rev. 18.01.2009 CmpE 583 Fall 2008

Rule Layer Work Rule Interchange Format initiative at W3C: See the charter Especially the RIF Use Cases and Requirements document. RuleML Initiative vied to merge with DAML, OASIS, W3C, or US/EU Joint Committee (JC) in search of a “home base” some years ago. Still independent! In effect, JC merged with DAML and later DAML+OIL merged with W3C. So now, OASIS, W3C & RuleML Initiative are still going their separate ways. 17.12.04 updated 28.12.06 CmpE 583 Fall 2008

Five Publications from RIF-WG of W3C The Rule Interchange Format (RIF) Working Group published five new Working Drafts today. Since the Last Call Working Draft of RIF Basic Logic Dialect (BLD), the group has been developing other key dialects, components, and test cases. The new publications are: RIF Use Cases and Requirements: minor changes RIF Core: new design to support both BLD and PRD RIF Datatypes and Built-Ins 1.0: various improvements RIF Production Rule Dialect (PRD): operational semantics are complete RIF Test Cases: early stages of test suite The Working Group is nearing Last Call on these remaining elements of RIF, and welcomes feedback from rulesystem users and designers. Please send comments by 23 January. Learn more about the Semantic Web Activity. Dated: 2008-12-19 11.01.2009 CmpE 583 Fall 2008

Where to Get More Information? [TBL-1998] TBL: Axioms of Web Architecture: Rules and facts: Inference Engines vs. Web. In Design issues. [RuleML Homesite] The Rule Markup Initiative: http://www.ruleML.org/ 17.12.04 updated 28.12.06 CmpE 583 Fall 2008