Copyright ©2008 BBN Technologies Use of SWRL for Ontology Translation Mike Dean Principal Engineer BBN Technologies [email protected].

Copyright ©2008 BBN Technologies

Use of SWRL for Ontology Translation

Mike DeanPrincipal EngineerBBN [email protected]


Assumptions

Technology – Intermediate– Familiarity with RDF and OWL

Desire to integrate multiple independent data sources using Semantic Web technologies

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Copyright ©2008 BBN Technologies 3

Outline Background Ontology Translation SWRL

– Demo of open source Snoggle tool

Other Approaches


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


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

2

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


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 ) ) ) . }


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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Copyright ©2008 BBN Technologies Use of SWRL for Ontology Translation Mike Dean Principal Engineer BBN Technologies [email protected].

Documents

bbn technologies use

bbn technologies snoggle

semantic web technologies

owl ontology

web ontology

swrl builtins

key data source

elses data source