1 CIS607, Fall 2005 Semantic Information Integration Instructor/Organizer: Dejing Dou Week 1 (Sept. 28)

2 About this Seminar Introduction Lectures – Week 1: General Introduction and Basic Knowledge (Semantics, Ontology, Database Schema, XML, the Semantic Web) – Week 2: Introduction to Each Topic Paper Presentations and Discussions – Week 3 to Week 9: Schema and Ontology Mapping/Matching, Schema and Ontology Integration/Merging, Data Integration and Translation, Semantic Query Processing and Semantic Search. Discussion of Applications – Enterprise Information Integration – Data Integration and Data Mining in Biomedical Informatics

3 Evaluation Attendance: 20% – However, 2 Absences or 4 Lateness without excuse  Fail Paper Reading and Discussion: 30% – Summary and Question Preparations (homework) – Asking Questions to Paper Presenter or Instructor Paper Presentation: 50% – Minutes Presentation – Minutes Question Answering

4 What is “ SII ” Semantic Information Integration – Semantic Information: Ontologies, Database Schemas… – Ontology and Schema Integration/Merging Semantic Information Integration – Consider Semantic Differences when Integrating Information (data). – Data Integration/Translation and Query Processing.

5 What is the Semantics of Data Informal Definition: Meanings of Data – It only sounds ok for human. One formal example: How to define the semantics of First Order Logic expressions. e.g.  x, y, z (father x y)  (father y z)  (grandfather x z)  x, z (grandfather x z) =>  y (father x y)  (parent y z) – What domain (D) is involved for the quantifiers to quantify for. – What is the interpretation (I) for the constant, function and predicate with respect to the domain. – Domain and Interpretation specify Model (M = ). – The assignment of values to variables when defining the truth of a formula and satisfaction of formulas.

6 Definition of Ontology Formal specification of a vocabulary of concepts and axioms relating them.

7 A Genealogy Ontology Individual Family Event Male Female MarriageEvent DivorceEvent DeathEvent BirthEvent husband childIn wife marriage divorce birth Gender sex Classes: Individual, Male,Female, Family, MarriageEvent… Properties: sex, husband, wife, birth…… Axioms: If there is a MarriageEvent, there will be a Family related to the husband and wife properties.

8 A Genealogy Ontology in Web-PDDL A genealogy ontology in Web-PDDL (a FOL language) looks like: (define (domain ged-ont) (:extends (uri “ :prefix drc)) (:types Individual Family Event - Object Male Female - Individual MarriageEvent - Event Gender - String…) (:predicates(sex p - Individual s - Gender) (husband f - Family h - Male) …) (:axioms (forall (x - MarriageEvent) (exists (y z – Individual f – family) (and (husband f y) (wife f z) (marriage f x)) …))

9 Database and Database Schemas Individual-nametitlesex Henry_VIKing of England“M” Margaret of Anjou Queen of England“F” FamliyMarriageEvent F1305ME1306 F1307ME1308 The Individual relation The marriage relation Individual-nameFamily Henry_VIF1305 Henry_VF1307 The husband relation

10 Definition in SQL (Structured Query Language) For those three relations: create table Individual (Individual-name char(20) not null, title char(30), sex char(20), primary key (Individual-name)) create table marriage (Family char(20) not null, MarriageEvent char(20) not null, primary key (Family, MarriageEvent)) create table husband (Family char(20) not null, Individual-name char(20), primary key (Family))

11 A Sample Relational Database

12 Current WWW The majority of data resources in WWW are in human readable format only (e.g. HTML). human WWW

13 XML: Extensible Markup Language Defined by the WWW Consortium (W3C) Originally intended as a document markup language not a database language The ability to specify new tags, and to create nested tag structures made XML a great way to exchange data, not just documents XML has become the basis for many new generation data interchange formats. A wide variety of tools is available for parsing, browsing and querying XML documents/data

14 XML (Cont ’ d) The ability to specify new tags, and to create nested tag structures made XML a great way to exchange data, not just documents. – Much of the use of XML has been in data exchange applications, not as a replacement for HTML. Some XML docs use DTD or XML Schemas Tags make data (relatively) self-documenting – E.g. A-101 Downtown 500 A-101 Johnson

15 The Semantic Web One major goal of the Semantic Web is that web-based agents can process and “understand” data[Berners-Lee etal01]. Ontologies formally describe the semantics of data and web-based agents can take web documents (e.g. in RDF, OWL) as a set of assertions and draw inferences from them. human SW Web-based agents

16 RDF and OWL Resource Description Framework (RDF) goes a step further to describe the “semantics” of data. – RDF use XML syntax but mark up data more formally into a set of “triples”. – Each triple, an RDF statement, is composed of a subject, a property and an object. The subject and property are each identified by a URI as RDF ID. John Smith … …

17 The Genealogy Ontology in OWL The genealogy ontology in OWL (Web Ontology Language) looks like: ……