use of swrl for ontology translation
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Copyright ©2008 BBN Technologies
Use of SWRL for Ontology Translation
Mike DeanPrincipal EngineerBBN Technologiesmdean@bbn.com
Copyright ©2008 BBN Technologies
Assumptions
Technology – Intermediate– Familiarity with RDF and OWL
Desire to integrate multiple independent data sources using Semantic Web technologies
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Outline Background Ontology Translation SWRL
– Demo of open source Snoggle tool
Other Approaches
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Presenter Background Principal Engineer at BBN Technologies (1984-present) Principal Investigator for DARPA Agent Markup Language (DAML)
Integration and Transition (2000-2005)– Chaired the Joint US/EU Committee that developed DAML+OIL and
SWRL Developer and/or Principal Investigator for many Semantic Web
tools, datasets, and applications (2000-present) Member of the W3C RDF Core, Web Ontology, and Rule
Interchange Format Working Groups– Co-editor of the W3C OWL Reference
Other SemTech presentations– Semantic Query: Solving the Needs of a Net-Centric Data Sharing
Environment (2007, w/ Matt Fisher)– Semantic Queries and Mediation in a RESTful Architecture (2008, w/
John Gilman and Matt Fisher)
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Ontology Translation
Data source -> domain ontologies– Data source ontology is an OWL representation of its
native data model– Domain ontology is an OWL ontology used by a
community of interest Mappings typically unidirectional and incomplete Common variations
– Use a key data source as the domain ontology– Generalize to n-levels, by employing a domain
ontology as someone else’s data source
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Types of Ontology Translation Renaming
– (data:Car ?x) => (domain:Vehicle ?x) Structural
– (family:Family ?f)(family:husband ?f ?h)(family:wife ?f ?w)=> (exfoaf:hasHusband ?w ?h)(exfoaf:hasWife ?h ?w)
Value Conversion– (data:length ?feet)
(swrlb:multiply ?inches ?feet 12)=> (domain:length ?inches)
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SWRL
Semantic Web Rule Language– Combines OWL, RuleML, and builtins – From the developers of OWL and RuleML
W3C Member Submission in 2004– Input to the W3C standardization process, not an
output (Recommendation) Current de facto standard for Semantic Web
Rules Numerous implementations
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SWRL Constructs
ClassAtom (?i ?c) DataRangeAtom (?d ?r) IndividualPropertyAtom (?i1 ?p ?i2) DatavaluedPropertyAtom (?i ?p ?d) SameIndividualsAtom (?i1 ?i2) DifferentIndividualsAtom (?i1 ?i2) BuiltinAtom (?op ?arg1 … ?argn)
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SWRL Builtins
See http://www.w3.org/Submission/SWRL/#8 for details
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Snoggle
Open source GUI SWRL editor focused on ontology translation
Can export SWRL/XML or SWRL/RDF– Extensible to other formats such as RIF
Available at http://snoggle.projects.semwebcentral.org
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Snoggle Demo
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Snoggle-GeneratedRules In Protégé 4
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SWRL Implementations SweetRules
– Translates to Jena Rules and implements builtins Protégé 3 and 4 TopBraid Composer Pellet KAON2 RacerPro INRIA Alignment API (export) RuleVISor and BaseVISor …
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SWRL Notes 1 Can also generally be used with RDF vocabularies as well as OWL
ontologies Nullable database columns each require their own SWRL
translation rule Most/all implementations support named classes only, referring to
externally defined classes and properties rather than internal OWL definitions
Most implementations use SWRL/RDF rather than SWRL/XML – a surprise to the authors– Process and store rules with ontologies
Most implementations assume that only the first argument of a builtin is unbound– SWRL builtins formally represent logical relationships, not function calls– (swrlb:subtract ?a ?b ?c) generally computes ?a = ?b - ?c not all
combinations of ?b and ?c that produce ?a
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SWRL Notes 2 Most applications employ some sort of user-
defined builtin(s) to generate a URI or bNode– Examples
• Generate a new Family instance from information about Individuals
• Generate a view (e.g. map point) for instance data• Construct a resolvable URI from database primary or foreign
key(s)• Translate a database column spouseName into a
foaf:Person with foaf:name and domain:spouse• Jena Rules makeTemp and makeInstance builtins
– Logicians worry about “head existential variables”– This should be standardized
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AsioTM Semantic Web Toolkit
SOAPWS
WSDL
WSDLOntology
OWL
Mapping Ontology
OWL
SWRL Rules
RDBMS
Domain Source Ontology
OWL
QueryDecomposition
Query: SPARQL1
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4 Data Access
3 Generation ofSub Queries
6Query Result Set
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Data Source Ontology
OWL
Data Source Ontology
OWL
Semantic BridgeDatabase
Semantic BridgeWeb Service
BackwardsRule Chaining
Snoggle
KB
Semantic Query Decomposition (SQD)
Semantic BridgeSPARQL Endpoint
Automapper
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Alternative Translation Approaches
OWL XSLT SPARQL OWL 2 RIF OWLED DL Safe Rules FOL Custom code
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History (My Perspective) The current W3C separation between ontologies
and rules is largely artificial– Precursor representations such as KIF and CycL
include both sets of constructs– Adding rules would have significantly delayed OWL
W3C agonized over the relationship between queries and rules before forming the DAWG (SPARQL) and RIF Working Groups– ~50% same/~50% different– W3C made the right decision, but should keep the
efforts aligned
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OWL W3C OWL Web Ontology Language Recommendation since 2004 + Includes basic mapping constructs
– subClassOf, equivalentClass– subPropertyOf, equivalentProperty– sameAs
+ Often sufficient for renaming - Usually insufficient by itself for ontology translation Many constructs can be expressed using either ontologies or rules
– Description Logic Programs (DLP) and subsequent extensions– Users often are more comfortable with one formalism than the other– Probably preferable to use one formalism for translation (rules)
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OWL Examples
data:Individual owl:equivalentClass domain:Person
data:SUV rdfs:subClassOf domain:Vehicle data:lastName owl:eqivalentProperty
foaf:surname
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XSLT
W3C Recommendation since 1999– XSLT 2.0 Recommendation since 2007
Widely used XML tool + Great for generating RDF from other
XML formats - Generally impractical for reading RDF
– No canonical RDF/XML serialization– Too many ways to say the same thing
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SPARQL SPARQL Query Language for RDF W3C Recommendation since January 2008 + CONSTRUCT queries can easily map from one
ontology to another ++ Concise representation when dealing with optional
values Supports a range of builtins similar to SWRL -- Multiple queries can’t naturally be composed (unlike
rules) - No intrinsic support for OWL
– SPARQL-DL proposal and Pellet prototype
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SPARQL Example
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PREFIX family: <http://asio.bbn.com/2008/05/semtech/family#>PREFIX exfoaf: http://asio.bbn.com/2008/05/semtech/exfoaf#
CONSTRUCT { ?husband exfoaf:hasWife ?wife . ?wife exfoaf:hasHusband ?husband . ?husband exfoaf:hasDaughter ?daughter . ?wife exfoaf:hasDaughter ?daughter . ?husband exfoaf:hasSon ?son . ?wife exfoaf:hasSon ?son . ?son exfoaf:hasFather ?husband . ?son exfoaf:hasMother ?wife . ?daughter exfoaf:hasFather ?husband . ?daughter exfoaf:hasMother ?wife . ?son exfoaf:hasSister ?daughter . ?daughter exfoaf:hasBrother ?son . ?son exfoaf:hasBrother ?son2 . ?daughter exfoaf:hasSister ?daughter2 . }WHERE { ?family a family:Family . OPTIONAL { ?family family:husband ?husband } . OPTIONAL { ?family family:wife ?wife } . OPTIONAL { ?family family:son ?son } . OPTIONAL { ?family family:daughter ?daughter } . OPTIONAL { ?family family:son ?son2 } . OPTIONAL { ?family family:daughter ?daughter2 } .
FILTER ( ( ! BOUND(?son) || ! BOUND(?son2) || ( ?son != ?son2 )) && ( ! BOUND(?daughter) || ! BOUND(?daughter2) || ( ?daughter != ?daughter2 ) ) ) . }
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OWL 2 W3C OWL Working Group formed in October 2007 to update
OWL based on user feedback– 2 OWL Experiences and Directions Workshops led to W3C
OWL 1.1 Member Submission in December 2006 6 Working Drafts published in April 2008
– Name changed to OWL 2 New features particularly relevant to translation
– Property chains– Data ranges– OWL-R – N-ary data predicates (may support comparisons and other
builtins) Largely already implemented in Pellet and other reasoners
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OWL 2 Examples(Functional-Style Syntax)
SubObjectPropertyOf( SubObjectPropertyChain(owns hasPart) owns)
SubObjectPropertyOf( SubObjectPropertyChain(parent brother) uncle)
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RIF
W3C Rule Interchange Format Working Group formed in December 2005
Brings together multiple communities: Semantic Web, production rule system vendors (iLog, Fair Isaac, …), OMG, business rules (SBVR, …)
Working Drafts published April 2008– + Addresses RDF and OWL compatibility
May eventually subsume SWRL - Very few current implementations
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RIF Example(BLD presentation syntax)
Forall ?family ?husband ?wife?husband # “foaf:Person^^rif:iri [“exfoaf:wife”^^rif:iri -> ?wife] :- ?family # “family:Family”^^rif:iri [“family:husband”^^rif:iri -> ?husband, “family:wife”^^rif:iri -> ?wife] Forall ?family ?husband ?wife?wife # “foaf:Person^^rif:iri [“exfoaf:husband”^^rif:iri -> ?husband] :- ?family # “family:Family”^^rif:iri [“family:husband”^^rif:iri -> ?husband, “family:wife”^^rif:iri -> ?wife]
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OWLED DL Safe (SWRL) Rules
OWLED Task Force Out of charter for WG OWL WG DL Safety means only working with
named individuals– Incomplete compared to full SWRL– Better computational properties
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FOL
First Order Logic– Common Logic (ISO 24707:2007)– CycL– …
+ Expressive power– Superset of OWL and SWRL
- Generally not focused on ontology translation - Builtin support, scalability, and/or portability may
be limited
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Custom Code
Gold standard– + Total flexibility– - Expensive
- Can’t reason over translation rules– Coverage– Data discovery– Maintenance
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Conclusions
SWRL is the current de facto standard for Semantic Web rules
SWRL works well for ontology translation SWRL rules can easily be translated to
other representations when necessary
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Additional Pointers
SWRL Member Submission– http://www.w3.org/Submission/SWRL/
Snoggle– http://snoggle.projects.semwebcentral.org
BBN Asio Toolkit– http://asio.bbn.com
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