OWL & Protege Introduction Dongfang Xu Ph.D student, School of Information, University of Arizona Sept 10, 2015

Agenda Brief OWL OWL elements OWL in OWL Protege

Brief OWL What is web Ontology Language ? 1. OWL is designed for use by applications; 2. To process the content of information; 3. OWL facilitates greater machine interpretability of Web content ; 4. Providing additional vocabulary along with a formal semantics compared with RDFs/RDF.

Why OWL? Brief OWL

Owl and RDF/RDFS 1. Requirements for Ontology languages; Formal semantics (describes meaning of language precisely) ; Reasoning support. (x  C; C subclass B. X  B. ) 2. Limitations of RDF Schema. Too focus on hierarchies. Fewer relationship rule. Reference: Antoniou, G., & Van Harmelen, F. (2008). A semantic web primer (2 nd ed.). Cambridge, Mass: MIT press.

Brief OWL Three Sublanguage of OWL 1. OWL Full Fully upward-compatible with RDF, both syntactically and semantically; undecidable, inefficient in reasoning support 2. OWL DL Essentially application of OWL’s constructor to each other is disallowed. 3. OWL Lite Some parts of OWL are excluded, like enumerated classes, disjoint statements, and arbitrary cardinality.

Agenda Brief OWL OWL elements OWL in OWL Protege

OWL Elements

OWL elements Syntax 1. An RDF’s XML-based syntax. Like example 2 2. An abstract syntax. Class (associate professor DisjointClasses(professor associate professor)) 3. Graphic syntax See in example1, RDF/RDFs graph

OWL elements Syntax Header 1. Namespaces <rdf: RDF xmlns: owl=“……” xmlns: rdf=“……”> …… 2. Asseration under an owl: Ontology Contain comments, version control, and also including other ontology, owl: imports, lists other ontology whose content is considered as part of current ontology.

OWL elements Syntax Header Class Elements 1. owl : class used to define class 2. owl: EquivalentClass (object property) owl: disjointWith

OWL elements Syntax Header Class Elements Property Elements 1. Object property Relate objects to other objects. 2. Data type property; Like “phone”, “age”.

OWL elements … Class Elements Property Elements Property Restriction ##has/someValues ##minCardinality

OWL elements … Property Elements Property Restriction Special Properties Owl: TransitiveProperty (is taller than) Owl: SymmetricProperty (has same …) Owl: FunctionalProperty (defines a property that has at most one value for each object) Owl: InverseFunctionalProperty (defines two different objects cannot have the same value)

OWL elements … Property Restriction Special Properties Boolean Combinations Define class use “unionOf”, “intersectionOf”, “complementOf”.

OWL elements … Special Properties Boolean Combinations Instances Like RDf

OWL elements

Agenda Brief OWL OWL elements OWL in OWL Protege

For each class or property, OWL defines each element as below: …… OWL in OWL

For each class or property, OWL defines each element as below: …… Instructions for how to use each element. OWL in OWL

Agenda Brief OWL OWL elements OWL in OWL Protege

Definition Protégé is a free, open source ontology editor and a knowledge acquisition system. Protege provides a graphic user interface to define ontologies. It also includes deductive classifiers to validate that models are consistent and to infer new information based on the analysis of an ontology., Protégé is a framework for which various other projects suggest plugins.

Protege Example

Protege Resource

Thank you! Q&A