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The RuleML Initiative, July/August 2001
International Semantic Web Working SymposiumSWWS-01
30 July - 1 August 2001, Stanford, California, USA
Harold Boley, Said Tabet and Gerd Wagner
Design Rationale of RuleML: A Markup Language for Semantic Web Rules
The RuleML Initiative, July/August 2001 2
Introduction and Background The RuleML Initiative as a Web Ontology Effort Modular Syntax & Semantics of RuleML RuleML DTDs: release 0.8 Negation Handling in RuleML Priorities/Evidences in RuleML RuleML Implementations via XSLT & Rule Engines Example: A Semantic Web Scenario in Insurance Conclusions
Agenda
The RuleML Initiative, July/August 2001 3
Introduction and Background
Semantic Web rules less studied than corresponding ontology (taxonomy) markup
Rule Markup Initiative fills this gap by exploring rule systems (e.g.,extended Horn logics) suitable for the Web:
Syntax (XML and RDF), semantics, tractability/efficiency, transformation, and compilation
• Derivation rules: may be evaluated bottom-up as in deductive databases, top-down as in logic programming, or by tabled resolution as in XSB• Reaction rules: also called "ECA" -- “Event-Condition-Action" -- or “Trigger" rules• Possible combinations
RuleML
The RuleML Initiative, July/August 2001 4
The RuleML Initiative as a Web Ontology Effort
RuleML Initiative: started in August 2000 during the Pacific Rim International Conference on Artificial Intelligence (PRICAI 2000)
February/March 2001: First RuleML BOF at W3C Plenary and WG Meeting event
Ontology ‘equation’: Ontology = Taxonomies + Axioms(with Axioms having the form of Rules) gives big picture
System of sublanguages: from RDF-like triples to a labeled Horn logic with equations plus URI individuals and relations
The RuleML Initiative, July/August 2001 5
Modular Syntax & Semantics of RuleML
Reaction Rules
1. 2.
Integrity Constraints Derivation Rules
3.
Facts
RuleML hierarchy top-level:
1. Integrity constraints: reaction rules that signal inconsistency when certain conditions are fulfilled
2. Derivation rules: reaction rules whose action happens to only 'assert' a conclusion when certain conditions (premises) are fulfilled
3. Facts: derivation rules with empty conjunction of premises
The RuleML Initiative, July/August 2001 6
Modular Syntax & Semantics of RuleML (Cont’d)
urc-bin-data-ground-facturc-bin-data-ground-log
urc-bin-datalog
bin-datalogurc-datalog
ur-datalog
ur-hornlog
ur-equalog
hornlog
equalog
datalog
ur
Rooted DAG will be extended withbranches for further sublanguages
URL/URI-like‘ur’-objects
derivation rules
RDF- like triples
ur-datalog = join(ur,datalog
)
Sublanguagehierarchy:
RDF Rules
The RuleML Initiative, July/August 2001 7
Modular Syntax & Semantics of RuleML (Cont’d)
Separation of concerns:Sublanguage hierarchy:
12 sublanguages together constitute modularized basic RuleML definition. Except 'UR' (URL/URI) group correspond to well-known rule systems, each with semantic (model- and proof-theoretic) characterizationConcrete markup:
In recent months, RuleML 0.7 DTDs have been developed into RuleML 0.8 DTDs without affecting the above semantics. The new markup uses XML in RDF's 'explicit role-markup' style, relativizing XML's positionality to places where RDF's Seq containers or DAML+OIL lists are used
The RuleML Initiative, July/August 2001 8
RuleML DTDs: release 0.8
<fact> <_head> <atom> <_opr><rel href="http://www.eeebizz.com/rdf-sch#Approval"/></_opr> <ind href="http://www.eeebico.org/docs/joint-mission.html"/> <ind>full</ind> </atom> </_head></fact>
RDF-like triple:
Advantage of roles is object-centered modeling: If some item is to be added to a fact or atom, then this is easy to attach, RDF-like
Item insertion, XML-like, into child sequence would cause all subsequent children to assume a new position (problem for XSLT)
roles
Concrete markup:
The RuleML Initiative, July/August 2001 9
Negation Handling in RuleML
IF isPresent(?someCar)
ANDNOT isAssignedToRentalOrder(?someCar)
ANDNOT requiresService(?someCar)
AND…
THEN isAvailable(?someCar)
The Closed-World Negation NOT
UML Diagram:
The RuleML Initiative, July/August 2001 10
Negation Handling in RuleML (Cont’d)
<_body> <and> <atom> <_opr><rel>isPresent</rel></_opr> <var>Car</var> </atom> <not> <atom> <_opr><rel>isAssignedToRentalOrder</rel></_opr> <var>Car</var> </atom> </not> . . . </and> </_body>
NOT in RuleML: an example
The RuleML Initiative, July/August 2001 11
Negation Handling in RuleML (Cont’d)
NOT = non-truth (or failure) NEG = falsity
Default rules:
IF NOT hasApproval(?URL)THEN NEG
isOfficialDocument(?URL)
Open-World Reasoning with NOT and NEG
The RuleML Initiative, July/August 2001 12
Priorities/Evidences in RuleML
Quantitative Priorities: Static numerical salience Dynamically calculated priorities
Qualitative PrioritiesUsing the Overrides Fact over rule labels
The RuleML Initiative, July/August 2001 13
Priorities/Evidences in RuleML (Cont’d)
<imp> <_rlab><ind>beginners</ind></_rlab> <_spriority><ind>0.75</ind></_spriority>
<_head> ....... </_head> <_body>
<atom> <_opr><rel>customerUnder25</rel></_opr>
<var>customer</var> </atom>
</_body></imp>
Static Salience Example:
The RuleML Initiative, July/August 2001 14
Priorities/Evidences in RuleML (Cont’d)
Dynamic Salience Example:
<imp> <_rlab><ind>beginners</ind></_rlab> <_dpriority><rel>calculateSalience</rel></_dpriority>
<_head> ....... </_head> <_body>
<atom><_opr><rel>customerUnder25</rel></_opr>
<var>customer</var> </atom>
</_body></imp>
The RuleML Initiative, July/August 2001 15
RuleML Implementations via XSLT & Rule
Engines
XSLT: is a Rule Based Language is a Transformation Tool for RuleML Knowledge
Bases (KB): Using Style sheets to exchange RuleML KBs
Implementations: With GEDCOM, Mike Dean created the first
operational RuleML (0.7) rulebase, where rules on family relationships (child, spouse, etc.) are run via XSLT translators to the XSB, JESS, and N3/cwm engines
With Mandarax RuleML, Jens Dietrich has implemented the first complete input-processing-output environment for RuleML (0.8)
The RuleML Initiative, July/August 2001 16
A Semantic Web Scenario in Insurance
A teenager after her first car accident:
how much will my premiums increase and how does this accident affect my insurance policy?
Principle: Uniform RuleML representation of derivation rules and underlying document metadata
The RuleML Initiative, July/August 2001 17
A Semantic Web Scenario in Insurance (Cont’d)
<imp> <_rlab><ind>beginners</ind></_rlab>
<_spriority><ind>0.75</ind></_spriority>
<_head> <atom> <_opr><rel>calculatePremium</rel></_opr> <var>customer</var> <ind>40</ind> </atom>
</_head> <_body><and>
<atom> <_opr><rel>InsurancePolicy</rel></_opr>
<var>customer</var><var>insurance</var>
</atom> <atom>
<_opr><rel>lifeEvent</rel></_opr> <var>customer</var><ind>accident</
ind><var>report</var> </atom>
<atom> <_opr><rel>customerUnder25</rel></_opr>
<var>customer</var>
</atom></and> </_body>
</imp>
The RuleML Initiative, July/August 2001 18
A Semantic Web Scenario in Insurance (Cont’d)
<imp> <_rlab><ind>family</ind></_rlab>
<_spriority><ind>0.9</ind></_spriority>
<_head> <atom> <_opr><rel>calculatePremium</rel></_opr> <var>customer</var><ind>0</ind> </atom>
</_head> <_body><and>
<atom> <_opr><rel>InsurancePolicy</rel></_opr>
<var>customer</var><var>insurance</var>
</atom> <atom>
<_opr><rel>lifeEvent</rel></_opr> <var>customer</var><ind>accident</
ind><var>report</var> </atom>
<atom> <_opr><rel>FamilyAutoPlan</rel></_opr>
<var>customer</var><var>familyauto</var>
</atom></and> </_body>
</imp>
The RuleML Initiative, July/August 2001 19
A Semantic Web Scenario in Insurance (Cont’d)
Formalizing the relevant facts
Olivia is under 25
Olivia has an insurance policy and this document has link .../IMA-0835:
Olivia is in a family auto plan and this document has link .../FMA-0142: Olivia's accident report is available at TrafficReport.biz : <fact>
<_head><atom> <_opr> <rel>FamilyAutoPlan</rel></_opr> <ind>Olivia</ind> <ind href = “http://www.BostonInsurance.com/policy/FMA-0142” /></atom>
</_head></fact>
<fact> <_head>
<atom> <_opr><rel>LifeEvent</rel></_opr> <ind>Olivia</ind> <ind>accident</ind> <ind href = “http://www.TrafficReport.biz/MA/report0712” /></atom>
</_head></fact>
<fact> <_head>
<atom> <_opr><rel>InsurancePolicy</rel></_opr> <ind>Olivia</ind> <ind href = “http://www.BostonInsurance.com/policy/IMA-0835” /></atom>
</_head></fact>
<fact> <_head>
<atom> <_opr><rel>customerUnder25</rel></_opr> <ind>Olivia</ind></atom>
</_head></fact>
The RuleML Initiative, July/August 2001 20
A Semantic Web Scenario in Insurance (Cont’d)
Conflict Resolution: using Meta facts (a la BRML)
<imp> <_rlab>
<ind>beginners</ind></_rlab>
. . .</imp>
<imp><_rlab>
<ind>family</ind></_rlab>
. . .</imp>
<fact> <_head>
<atom>
<_opr><rel>Overrides</rel></_opr> <ind>family</ind> <ind>beginners</ind></atom>
</_head></fact>
The RuleML Initiative, July/August 2001 21
A Semantic Web Scenario in Insurance (Cont’d)
Conflict Resolution: using Meta facts (a la BRML)
<imp> <_rlab>
<ind>beginners</ind></_rlab>
. . .</imp>
<imp> <_rlab>
<ind>family</ind></_rlab>
. . .</imp>
<fact> <_head>
<atom>
<_opr><rel>Overrides</rel></_opr> <ind>family</ind> <ind>beginners</ind></atom>
</_head></fact>
The RuleML Initiative, July/August 2001 22
Conclusions
RuleML rulebases embedded in, or referring to, XML and RDF documents.
Using RuleML in other XML namespaces (like for, say, MathML), incl.
RDF(S) namespaces (ruleml: namespace prefix)
RuleML rule premises could be DAML+OIL concept descriptions orUML object descriptions
RuleML derivation rules integrated with reaction rules, e.g. Situated LP or ECA Framework (see SpiritSoft Demo)
RuleML and RDF Query talking about a joint Rule and Query effort as part of W3C Ontology Working Group
Ontologies:The big Picture and future RuleML Versions
The RuleML Initiative, July/August 2001 23
Conclusions (Cont’d)
IJCAI 01: two tutorials, a workshop and an invited talk,August 2001, Seattle, USA
ICEC 01 (International Conference on Ecommerce) panel,November 2001, Vienna, Austria
Dagstuhl seminar on Rule Markup Techniques: February 2002, Schloss Dagstuhl, Germany
Some RuleML events