Dept Computer Science Korea Univ Intelligent Information System

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Dept. Computer Science, Korea Univ. Intelligent Information System Lab. Ontology Languages Sohn Jong-Soo Intelligent

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. Ontology Languages Sohn Jong-Soo Intelligent Information System lab. Department of Computer Science Korea University 1

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. Index 1. 2. 3. 4.

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. Index 1. 2. 3. 4. 5. 6. Ontology XML RDF OIL DAML OWL 2

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 1. Ontology n Definition :

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 1. Ontology n Definition : Formal, explicit specification of a a shared conceptualization n Ontology can be used and shared by agents n Ontology languages ■ To be understood by humans intuitively ■ Capturing of meaning (semantics) of data ■ Inference mechanism with completeness, preciseness and efficiency ■ Interoperability and compatibility § Combined with web languages s. a. XML and RDF 3

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 1. Ontology n Crucial role

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 1. Ontology n Crucial role in enabling web-based knowledge processing, sharing and reuse ■ Human-beings and machines communicate each other § common understanding of topics between people and applications 4

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 1. Ontology n Conceptual structures

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 1. Ontology n Conceptual structures for machine processible data on the web ■ Formal tools to structure semantic data ■ Formal conceptualizations of particular domains n Metadata schema with controlled vocabulary of concepts ■ Semantic metadata for web pages ■ RDF & RDFS as metadata formats 5

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 2. XML (e. Xtensible Markup

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 2. XML (e. Xtensible Markup Language) n Standard markup language to represent the userdefined markup language n meta markup language ■ Markup language to define another markup language n Simple, but flexible text-format defined from SGML n Large-scale electronic publishing to meet the role in the exchange of wide variety of data on the web and elsewhere n Hierarchical structure with tag (DTD) DTD XML Style language Document Structure (Markup Language) Document Contents (instance) Style sheet 6

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 2. XML (e. Xtensible Markup

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 2. XML (e. Xtensible Markup Language) n XML related standards ■ DTD (Document Type Definition) § Defines the logic structure of XML documents § Defines contents & attributes of each component § Defines objects ■ XSL (e. Xtensible Style Sheet) § Defines the style to each component of XML documents § Documents transformation ■ CSS (Cascading Style Sheet) § Some functionality as XSL § Limitation in the style definition 7

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 2. XML (e. Xtensible Markup

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 2. XML (e. Xtensible Markup Language) n Advantages ■ ■ Data representation structured & independent Data sharing and interoperability Hierarchical, composite data n Disadvantages ■ Lack of representation of relationship between objects ■ Lack of representation of data meaning ■ Lack of inheritance of meaning 8

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 3. RDF (Resource Description Framework)

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 3. RDF (Resource Description Framework) n Markup language based on XML syntax n Developed to representation the multiple, various resources dispersed in the distributed web environment n Used as a basis for the other markup language n Data representation : triple representation as follow n <object, property, value> 9

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 3. RDF (Resource Description Framework)

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 3. RDF (Resource Description Framework) n Advantages ■ Representation of data with the meaning ■ Environment in which computer can understand process the data ■ Flexible capability to representation the meta data ■ Mean of information exchange in heterogeneous distributed environment ■ Description of constants by the semantic network n Disadvantages ■ Lack of affection inference mechanism ■ Weak in the representation of semantic of data 10

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 3. RDF (Resource Description Framework)

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 3. RDF (Resource Description Framework) <rdf: RDF xmlns: rdf="http: //www. w 3. org/1999/02/22 -rdf-syntax-ns#" xmlns: s="http: //iis. korea. ac. kr/schema/"> <rdf: Description about="http: //iis. korea. ac. kr/Home/Sohn"> <s: Creator> <rdf: Description about="http: //iis. korea. ac. kr/std. Id/2005020626"> <rdf: type resource="http: //iis. korea. ac. kr/schema/Person"/> <v: Name>Sohn Jong. Soo</v: Name> <v: Email>mis [email protected] ac. kr</v: Email> </rdf: Description> </s: Creator> </rdf: Description> </rdf: RDF> 11

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 4. OIL (Ontology Inference Layer)

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 4. OIL (Ontology Inference Layer) n Satisfies the requirement of semantic web n Hierarchical layer structure for extension 12

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 4. OIL (Ontology Inference Layer)

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 4. OIL (Ontology Inference Layer) n Based on Frame-based System, Description Logic and Web Languages Description Logics: Formal Semantics& Reasoning Support Frame-based system: Epistemological Modeling Primitives OIL Web language: XML and RDF-based syntax 13

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 4. OIL (Ontology Inference Layer)

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 4. OIL (Ontology Inference Layer) n Advantages ■ Hierarchical extensions ■ Effective inference mechanism based on the Description Logic ■ Well-defined semantics n Disadvantages ■ Impossible to define the default-value ■ Impossible to provide the meta-class ■ Impossible to support the concrete domain § Limitation in the OIL extension and ontology transformation 14

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 5. DAML (DARPA Agent Markup

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 5. DAML (DARPA Agent Markup Language) n Based on XML and RDF n Combines the advantage of various, multiple semantic web languages ■ Combination of DAML + OIL ■ DAML-S § Automatic Web Service retrieval and execution ■ DAML-L § Logic representation 15

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 5. DAML (DARPA Agent Markup

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 5. DAML (DARPA Agent Markup Language) n Advantages ■ ■ Powerful in the representation of meaning and constraints Support for the XML-Schema data type Support well-defined semantics Support default value n Disadvantages ■ Can’t exclude the RDF and XML ■ Can’t be formal language ■ Less extensible compared with OIL 16

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 5. DAML (DARPA Agent Markup

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 5. DAML (DARPA Agent Markup Language) <? xml version=” 1. 0”? > <rdf: RDF xmlns: rdf=”http: //www. w 3. org/1999/02/22/-rdf-syntzs-ns#” xmlns: rdfs=”http: //www. w 3. org/TR/1999/PR-rdf-schema-19990303#” xmlns: daml=”http: //www. daml. org/2001/03/daml+oil#” xmlns = “http: //www. daml. org/2001/03/daml+oil#”> <daml: Ontology rdf: about=””> <daml: version. Info>1. 0</daml: version. Info> <daml: import rdf: resource=”http: //schema. org/base# “/> </daml: Ontology> <daml: Class rdf: ID=”boy-friend”> <rdfs: sub. Classof rdf: resource=”#Male” /> <rdfs: sub. Class. Of> <daml: on. Property rdf: resource=”@has” /> <daml: has. Class redf: resource=”#girl-friend” /> </rdfs: sub. Class. Of> </daml: Class> <daml: Class rdf: ID=”Animal”> <rdfs: label>Animal</rdfs: label> </daml: Class> <daml: Class rdf: ID=”girl-friend”> <rdfs: sub. Class. Of rdf: resource=”#Female”/> </daml: Class> <daml: Class rdf: ID=”Male”> <rdfs: sub. Class. Of rdf: resource=”#Animal”/> <daml: disjoint. With rdf: resource=”#Female”/> </daml: Class> <daml: Class rdf: ID=”Female”> <rdfs: sub. Class. Of rdf: resource=”#Animal”/> <daml: disjoint. With rdf: resource=”#Male”/> </daml: Class> </rdf: RDF> 17

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 6. OWL (Web Ontology Language)

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 6. OWL (Web Ontology Language) n Three species of OWL ■ OWL full is union of OWL syntax and RDF ■ OWL DL restricted to FOL fragment (¼ DAML+OIL) ■ OWL Lite is “easier to implement” subset of OWL DL n Semantic layering ■ DL semantics officially definitive n OWL DL based on SHIQ Description Logic ■ In fact it is equivalent to SHOIN(Dn) DL n OWL DL Benefits from many years of DL research ■ ■ Well defined semantics Formal properties well understood (complexity, decidability) Known reasoning algorithms Implemented systems (highly optimised) 18

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 6. OWL (Web Ontology Language)

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 6. OWL (Web Ontology Language) n Relationships between classes ■ equivalent. Class ■ sub. Class. Of ■ Intersection, union, complement, disjunction n Relationships between instances ■ same. As, different. From n Properties of properties ■ ■ ■ Domain, Range Cardinality Transitive, Symmetric all. Values. From, some. Values. From Functional, Inverse. Functional n Relationships between properties ■ sub. Property. Of ■ inverse. Of 19

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 6. OWL (Web Ontology Language)

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. 6. OWL (Web Ontology Language) RDFS syntax <owl: Class> <owl: intersection. Of rdf: parse. Type=" collection"> <owl: Class rdf: about="#Person"/> <owl: Restriction> <owl: on. Property rdf: resource="#has. Child"/> <owl: to. Class> <owl: union. Of rdf: parse. Type=" collection"> <owl: Class rdf: about="#Doctor"/> <owl: Restriction> <owl: on. Property rdf: resource="#has. Child"/> <owl: has. Class rdf: resource="#Doctor"/> </owl: Restriction> </owl: union. Of> </owl: to. Class> </owl: Restriction> </owl: intersection. Of> </owl: Class> 20

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. Thank you 22

Dept. Computer Science, Korea Univ. Intelligent Information System Lab. Thank you 22