Simplified Approach for Representing Part-Whole Relations in OWL-DL Ontologies A.Aziz Altowayan and Lixin Tao Pace University IEEE BigDataSecurity, 2015 Aug. 24, 2015
Ontology and Knowledge Representation Representation Problem in OWL Proposed Alternative Conclusion Outline Ontology and Knowledge Representation 1 Ontology for representing knowledge Ontology Relations OWL: Representing and Reasoning Representation Problem in OWL 2 Scenario Current Approach (W3.org Best Practice) Proposed Alternative 3 Proposed Approach Comparison and Demo Conclusion 4 Limitations and Future Work A.Aziz Altowayan and Lixin Tao
Ontology and Knowledge Representation Ontology for representing knowledge Representation Problem in OWL Ontology Relations Proposed Alternative OWL: Representing and Reasoning Conclusion Ontology and Knowledge Representation Why we need to represent knowledge? Definition: an ontology formally represents knowledge as a set of concepts within a domain, using a shared vocabulary to denote the types, properties and interrelationships of those concepts. (Wikipedia) Goals for having ontology (AI systems): What is this ? ( Representation ). How this relates to that ? ( Inference ). A.Aziz Altowayan and Lixin Tao
Ontology and Knowledge Representation Ontology for representing knowledge Representation Problem in OWL Ontology Relations Proposed Alternative OWL: Representing and Reasoning Conclusion Ontology and Knowledge Representation Example of an ontology model Sample ontology for a human body anatomy A.Aziz Altowayan and Lixin Tao
Ontology and Knowledge Representation Ontology for representing knowledge Representation Problem in OWL Ontology Relations Proposed Alternative OWL: Representing and Reasoning Conclusion IS-A and Part-Whole Relations Class hierarchy We are focusing on two types of ontology taxonomy: Generalization-based (e.g. Heart is an Organ) Partonomic-based (e.g. Retina is part of the Eye) A.Aziz Altowayan and Lixin Tao
Ontology and Knowledge Representation Ontology for representing knowledge Representation Problem in OWL Ontology Relations Proposed Alternative OWL: Representing and Reasoning Conclusion TBox vs. ABox Statements Definitions Terminological Box and Assertional Box Statements TBox: Relations Between Concepts, e.g. Every Car is a Vehicle. ∀ Car ⊑ Vehicle An Engine is part of a Vehicle. Engine ⊑ CarPart OR Engine ⊑ ∃ partOf Vehicle ABox: Assertion Sentences (between an instance and concept), e.g. BMW is a Car. Car(BMW) TBox + ABox = Knowledge Base A.Aziz Altowayan and Lixin Tao
Ontology and Knowledge Representation Ontology for representing knowledge Representation Problem in OWL Ontology Relations Proposed Alternative OWL: Representing and Reasoning Conclusion OWL Building ontology Web Ontology Language: OWL is a family of knowledge representation languages for authoring ontologies (Semantic Web). Description Logics: DL (variant of FOL) used in OWL to specify the semantics of a relation. “Reasoning in ontologies and knowledge bases is one of the reasons why a specification needs to be formal one.” A.Aziz Altowayan and Lixin Tao
Ontology and Knowledge Representation Representation Problem in OWL Scenario Proposed Alternative Current Approach (W3.org Best Practice) Conclusion What is the Problem ? Let’s introduce the problem through a simple Use Case. A.Aziz Altowayan and Lixin Tao
Ontology and Knowledge Representation Representation Problem in OWL Scenario Proposed Alternative Current Approach (W3.org Best Practice) Conclusion Scenario For representing a simple IS-A and Part-Of relations in OWL Example: How to assert the following model? In words, Car class as a generalization of ( is a ) Vehicle class, and Engine class as a component of ( part of ) Vehicle class. A.Aziz Altowayan and Lixin Tao
Ontology and Knowledge Representation Representation Problem in OWL Scenario Proposed Alternative Current Approach (W3.org Best Practice) Conclusion Scenario For representing a simple IS-A and Part-Of relations in OWL . . . IS-A relation (very simple way) : Example <owl:Class rdf:about="ns#Car"> <rdfs: subClassOf rdf:resource="ns#Vehicle"/> </owl:Class> Part-Whole relation: . . . OWL does not provide simple (and straightforward) primitives for part-whole relations. A.Aziz Altowayan and Lixin Tao
Ontology and Knowledge Representation Representation Problem in OWL Scenario Proposed Alternative Current Approach (W3.org Best Practice) Conclusion Why is that? Difficulty in representing part-whole relations Because, Part-Whole relations are variants (many different forms). Thus Some constraints (e.g. transitivity, cardinality) need to be imposed to specify the semantic of the relation. C. M. Keet and A. Artale, Representing and reasoning over a taxonomy of part-whole relations, Applied Ontology, vol. 3, Jan. 2008 A.Aziz Altowayan and Lixin Tao
Ontology and Knowledge Representation Representation Problem in OWL Scenario Proposed Alternative Current Approach (W3.org Best Practice) Conclusion Current Approach For representing Part-Whole in OWL The Current Approach provides a manual implementation of the underlying steps (thus a long and error-prone process) for achieving a single task. A.Aziz Altowayan and Lixin Tao
Ontology and Knowledge Representation Representation Problem in OWL Scenario Proposed Alternative Current Approach (W3.org Best Practice) Conclusion Current Approach Three steps implemented separately and manually Create an objectProperty (i.e. partOf) with specifying the 1 characteristics it holds. Create a new part-aggregating class (i.e. VehiclePart) to represent the 2 parts type. And (using OWL-DL) make it: equivalentClass to the restriction partOf some Vehicle . e.g. carPart ≡ ∃ partOf Vehicle Extend the part Class Engine to cope with the constraints. By using 3 OWL-DL to: make it a subClassOf of the restriction partOf some Vehicle . e.g. Engine ⊑ ∃ partOf Vehicle A.Aziz Altowayan and Lixin Tao
Ontology and Knowledge Representation Representation Problem in OWL Scenario Proposed Alternative Current Approach (W3.org Best Practice) Conclusion Current Approach The three steps serialized in RDF/XML syntax Example <!-- Step 1 --> <owl: ObjectProperty rdf:about="∂partOf"> <rdf:type rdf:resource="&owl; TransitiveProperty "/> </owl: ObjectProperty > <!-- Step 2 --> <owl:Class rdf:about="ns# VehiclePart "> <owl: equivalentClass > <owl: Restriction > <owl:onProperty rdf:resource="ns#partOf"/> <owl: someValuesFrom rdf:resource="ns#Vehicle"/> </owl: Restriction > </owl: equivalentClass > </owl:Class> <!-- Step 3 --> <owl:Class rdf:about="ns#Engine"> <rdfs: subClassOf> <owl: Restriction > <owl: onProperty rdf:resource="ns#partOf"/> <owl: someValuesFrom rdf:resource="ns#Vehicle"/> </owl: Restriction > </rdfs: subClassOf > </owl:Class> A.Aziz Altowayan and Lixin Tao
Ontology and Knowledge Representation Representation Problem in OWL Proposed Approach Proposed Alternative Comparison and Demo Conclusion Proposed Approach Simplifying Part-Whole Relations in OWL Integrate the three steps into a single line i.e. part-whole relations in a similar manner to subClassOf , as follows: Example <owl:Class rdf:about="ns#Engine"> <relation:partOf transitive ="yes" rdf:resource="ns#Vehicle"/> </owl:Class> Then, automatically 1 extract and build the relation’s constraints. 1Using pyowl module. A.Aziz Altowayan and Lixin Tao
Ontology and Knowledge Representation Representation Problem in OWL Proposed Approach Proposed Alternative Comparison and Demo Conclusion Proposed Approach Work flow of our method Simplified Relations Using OWL’s Annotations ↓ Extraction and Transformation Relation ↔ Elements Mapping ↓ Generate Final layout Standardized RDF/XML A.Aziz Altowayan and Lixin Tao
Ontology and Knowledge Representation Representation Problem in OWL Proposed Approach Proposed Alternative Comparison and Demo Conclusion Proposed Approach Simple Conceptual Model A.Aziz Altowayan and Lixin Tao
Ontology and Knowledge Representation Representation Problem in OWL Proposed Approach Proposed Alternative Comparison and Demo Conclusion Transformation Method Mapping stage 1 Extend current class to be a subClassOf its declared parent Example <owl:Class rdf:about="onto#Engine"> <!-- Auto generated mapping --> <rdfs: subClassOf> <owl: Restriction > <owl: onProperty rdf:resource="onto#partOf"/> <owl: someValuesFrom rdf:resource="onto#Vehicle"/> </owl: Restriction > </rdfs: subClassOf > <!-- End mapping --> </owl:Class> A.Aziz Altowayan and Lixin Tao
Ontology and Knowledge Representation Representation Problem in OWL Proposed Approach Proposed Alternative Comparison and Demo Conclusion Transformation Method Mapping stage 2 Generate an objectProperty for the relation Example <!-- Property --> <!-- Auto generated mapping --> <owl: ObjectProperty rdf:about="onto#partOf"> <rdf:type rdf:resource="&owl; TransitiveProperty "/> </owl: ObjectProperty > <!-- End mapping --> A.Aziz Altowayan and Lixin Tao
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