Digital Enterprise Research Institute www deri ie The

Digital Enterprise Research Institute www. deri. ie The Elephant, the Blind Men, and the Semantic Web Stefan Decker stefan. decker@deri. org http: //www. stefandecker. org/ Copyright 2008 Digital Enterprise Research Institute. All rights reserved.

Wikipedia… Digital Enterprise Research Institute www. deri. ie The Semantic Web is an evolving extension of the World Wide Web in which the semantics of information and services on the web is defined, making it possible for the web to understand satisfy the requests of people and machines to use the web content. It derives from World Wide Web Consortium director Sir Tim Berners-Lee's vision of the Web as a universal medium for data, information, and knowledge exchange 2

“Ho! what have we here … Digital Enterprise Research Institute www. deri. ie … So very round and smooth and sharp? To me 'tis very clear This wonder of an Elephant Is very like a spear!”… ¨ John Godfrey Saxe (1816 -1887) “The Blind Men and the Elephant” 3

Digital Enterprise Research Institute www. deri. ie Evolution of the Web Knowledge Representation Data Integration 4

Digital Enterprise Research Institute Semantic Web as an Evolution of the Web: A Quick History of Collaboration and Personal Information Management Tools (and Visions) 5 www. deri. ie

Cave Drawings 30000 BC Digital Enterprise Research Institute www. deri. ie

Writing: 3200 BC (Sumerian cuneiform) Digital Enterprise Research Institute www. deri. ie

Printing Press (Gutenberg 1450) Digital Enterprise Research Institute www. deri. ie

Photography (Daguerre 1839) Digital Enterprise Research Institute www. deri. ie

Telephone (Bell 1876) Digital Enterprise Research Institute www. deri. ie This 'telephone' has too many shortcomings to be seriously considered as a means of communication. The device is inherently of no value to us. ” Western Union internal memo, 1876.

Phonograph (Edison 1877) Digital Enterprise Research Institute “The end of books”. www. deri. ie

Movies (Lumiere 1895) Digital Enterprise Research Institute www. deri. ie

Wireless (radio) (Tesla 1891 or Marconi 1895) Digital Enterprise Research Institute www. deri. ie

Bush’s camera on the head Digital Enterprise Research Institute www. deri. ie

Memex Digital Enterprise Research Institute www. deri. ie Posited by Vannevar Bush in “As We May Think” The Atlantic Monthly, July 1945 “A memex is a device in which an individual stores all his books, records, and communications, and which is mechanized so that it may be consulted with exceeding speed and flexibility” Supports: Annotations, links between documents, and “trails” through the documents “yet if the user inserted 5000 pages of material a day it would take him hundreds of years to fill the repository, so that he can be profligate and enter material freely” 15

Sketch of memex Digital Enterprise Research Institute www. deri. ie 16

Video Conferencing (Bell Picturephone 1956) Digital Enterprise Research Institute www. deri. ie

Digital Enterprise Research Institute www. deri. ie Computer Aided Collaboration and Personal Information Management Tools (and Visions) 18

o. NLine System- NLS, 1968 (Doug Englebart, SRI) Digital Enterprise Research Institute The Mouse; Word Processing; Data Sharing; Hypertext; www. deri. ie

Digital Enterprise Research Institute 20 www. deri. ie

ARPANET (1969) (John Postel, David Crocker, Vint Cerf) Digital Enterprise Research Institute www. deri. ie

EMAIL (Ray Tomlinson 1971) Digital Enterprise Research Institute www. deri. ie

Xanadu (Ted Nelson ~1960 -? ? ? ) Digital Enterprise Research Institute 23 www. deri. ie

Graphical User Interface (1984) Digital Enterprise Research Institute www. deri. ie

World Wide Web (Tim Berners-Lee 1989) Digital Enterprise Research Institute www. deri. ie

Web-based Groupware (BSCW, 1994) Digital Enterprise Research Institute www. deri. ie

Wiki (Cunningham, 1995) Digital Enterprise Research Institute www. deri. ie

Instant Messaging (ICQ, 1995) Digital Enterprise Research Institute 28 www. deri. ie

“Academic” Semantic Web (1999) Digital Enterprise Research Institute www. deri. ie

Web 2. 0 and Online Social Networks (~2002) Digital Enterprise Research Institute www. deri. ie

On the shoulders of giants… Digital Enterprise Research Institute Memex (Vannevar Bush) A memex is “a device in which an individual stores all his books, records, and communications. ” Augmenting Human Intellect (Doug Engelbart) “By "augmenting human intellect" we mean increasing the capability of a man to approach a complex problem situation, to gain comprehension to suit his particular needs, and to derive solutions to problems. ” WWW (Tim Berners-Lee) “There was a second part of the dream […] we could then use computers to help us analyse it, make sense of what we re doing, where we individually fit in, and how we can better work together. ” 31 of 46 www. deri. ie

It wasn’t the time then… Digital Enterprise Research Institute www. deri. ie Where are we now? 32 of 46

Now we are making progress… Digital Enterprise Research Institute 33 of 46 www. deri. ie

A Network of Knowledge… Digital Enterprise Research Institute Interconnected n Universal n All encompassing www. deri. ie n Enable global and local collaboration n The right information for the right people at the right time n 34 of 46

Hypothesis Digital Enterprise Research Institute www. deri. ie n Collaborative access to networked knowledge assists with collective problem solving n enabling innovation and increased productivity n individual, organisational and global levels Inspired by Doug Engelbart’s original 1962 report of: AUGMENTING HUMAN INTELLECT: A CONCEPTUAL FRAMEWORK 35 of 49

Digital Enterprise Research Institute Semantic Web as Information Integration 36 www. deri. ie

A Problem Digital Enterprise Research Institute n www. deri. ie Often people build databases in isolation, then want to share their data Different systems within an enterprise ¨ Different information brokers on the Web ¨ Scientific collaborators ¨ Researchers who want to publish their data for others to use ¨ n Even with normalization and the same needs, different people will arrive at different schemas n Goal of data integration: tie together different sources, controlled by many people, under a common schema

Virtual Integration Architecture Digital Enterprise Research Institute www. deri. ie Sources can be: relational, hierarchical (IMS), structure files, web sites. 38

Challenge: Sources Without a Well. Structured Schema Digital Enterprise Research Institute • semistructured – irregular – deeply nested – cross-referenced • incomplete schema knowledge – autonomous – dynamic • • • Examples www. deri. ie HTML pages SGML documents genome data chemical structures bibliographic information results of the integration process

The Semistructured Data Model (e. g. Object Exchange Model) Digital Enterprise Research Institute www. deri. ie Bib &o 1 complex object paper book references &o 12 &o 24 references author title year &o 29 references author http page author title publisher title author &o 43 &25 &96 1997 firstname lastname atomic object last firstname &243 “Serge” “Abiteboul” “Victor” lastname first &206 “Vianu” 122 133

Research Projects (mid/late 1990/early 2000) Digital Enterprise Research Institute n n n n n Garlic (IBM), Information Manifold (AT&T) Tsimmis, Info. Master (Stanford) The Internet Softbot/Razor/Tukwila (UW) Hermes (Maryland) DISCO (INRIA, France) SIMS/Ariadne (USC/ISI) Emerac/Havasu (ASU) Bib. Finder (ASU) Kambhampati & Knoblock Information Integration on the Web (MA-1) 41 www. deri. ie

Many Techniques not Used for the Semantic Web Digital Enterprise Research Institute www. deri. ie n Local as View/Global as View n Wrapper/Mediator generation Kambhampati & Knoblock Information Integration on the Web (MA-1) 42

Digital Enterprise Research Institute Semantic Web as Knowledge Representation 43 www. deri. ie

Origins Digital Enterprise Research Institute Tim Berners-Lee’s original 1989 WWW proposal described a web of relationships among named objects unifying many info. management tasks. Capsule history n n n www. deri. ie Guha’s MCF (~94) XML+MCF=>RDF (~96) RDF+OO=>RDFS (~99) RDFS+KR=>DAML+OIL (00) W 3 C’s SW activity (01) W 3 C’s OWL (03) http: //www. w 3. org/History/1989/proposal. html

TBL’s semantic web vision Digital Enterprise Research Institute www. deri. ie

What is an Ontology? Digital Enterprise Research Institute n www. deri. ie What is an Ontology? „An ontology is a specification of a conceptualization. “ Tom Gruber, 1993 n n Ontologies are social contracts ¨ Agreed, explicit semantics ¨ Understandable to outsiders ¨ (Often) derived in a community process Vs. Database schema ¨ n Vs. XML Schema ¨ 46 Targeted towards physical data independence Targeted towards document structure

RDF Schema (RDFS) Digital Enterprise Research Institute n www. deri. ie RDF Schema adds taxonomies for classes & properties sub. Class and sub. Property n and some metadata. ¨ domain and range constraints on properties n Several widely used KB tools can import and export in RDFS ¨ Stanford Protégé KB editor • Java, open sourced • extensible, lots of plug-ins • provides reasoning & server capabilities

RDFS supports simple inferences Digital Enterprise Research Institute New and Improved! 100% Better www. deri. ie than XML!! An RDF ontology plus some RDF statements may imply additional RDF statements. n This is not true of XML. n Note that this is part of the data model and not of the accessing or processing code. n @prefix rdfs: <http: //www. . . >. @prefix : <genesis. n 3>. parent rdfs: domain person; rdfs: range person. mother rdfs: sub. Property parent; rdfs: domain woman; rdfs: range person. eve mother cain. parent a property. person a class. woman sub. Class person. mother a property. eve a person; a woman; parent cain a person.

Problems with RDFS Digital Enterprise Research Institute www. deri. ie n. RDFS too weak to describe resources in sufficient detail, e. g. : ¨No localised range and domain constraints ¨No existence/cardinality constraints ¨No transitive, inverse or symmetrical properties Can’t say that the range of has. Child is person when applied to persons and elephant when applied to elephants Can’t say that all instances of person have a mother that is also a person, or that persons have exactly 2 parents Can’t say that is. Part. Of is a transitive property, that has. Part is the inverse of is. Part. Of or that touches is symmetrical n. We need RDF terms providing these and other features.

DAML+OIL = RDF + KR Digital Enterprise Research Institute n. DAML www. deri. ie = Darpa Agent Markup Language ¨ DARPA program with 17 projects & an integrator developing language spec, tools, applications for SW. n. OIL = Ontology Inference Layer ¨ An EU effort aimed at developing a layered approach to representing knowledge on the web. n. Process ¨ Joint Committee: US DAML and EU Semantic Web Technologies participants DAML+OIL ¨ DAML+OIL specs released in 2001 ¨ See http: //www. daml. org/ ¨ Includes model theoretic and axiomatic semantics

W 3 C’s Web Ontology Language (OWL) Digital Enterprise Research Institute www. deri. ie DAML+OIL begat OWL. n OWL released as W 3 C recommendation 2/10/04 n See http: //www. w 3. org/2001/sw/Web. Ont/ for OWL overview, guide, specification, test cases, etc. n Three layers of OWL are defined of decreasing levels of complexity and expressiveness ¨ OWL Full is the whole thing OWL ¨ OWL DL (Description Logic) introduces restrictions ¨ OWL Lite is an entry level language intended to be easy to understand implement n

Owl is based on Description Logic Digital Enterprise Research Institute www. deri. ie n DL is a family of KR languages that might be described as “Logic meets Objects” n A DL is characterized by a set of constructors that allow one to build complex concepts and roles from atomic ones ¨Concepts objects correspond to classes; interpreted as sets of ¨Roles correspond to relations; interpreted as binary relations on objects n Axioms assert facts about concepts, roles and individuals n Distinguished by: ¨Formal ¨Sound ¨Many semantics for a decidable fragment of FOL and complete decision procedures for key problems implemented systems, some highly optimized

A Network of Knowledge… Digital Enterprise Research Institute Interconnected n Universal n All encompassing www. deri. ie n Enable global and local collaboration n The right information for the right people at the right time n 53 of 46

Digital Enterprise Research Institute www. deri. ie Issues? 54

Human Centric Digital Enterprise Research Institute 55 www. deri. ie

…Science… Digital Enterprise Research Institute 56 www. deri. ie

…Business Digital Enterprise Research Institute 57 of 34 www. deri. ie

Healthcare… Digital Enterprise Research Institute 58 www. deri. ie

…Government… Digital Enterprise Research Institute 59 www. deri. ie

Mobile Devices Digital Enterprise Research Institute 60 www. deri. ie

Widgets and Services Digital Enterprise Research Institute 61 www. deri. ie

Sensors are coming … Digital Enterprise Research Institute www. deri. ie “Soon we’ll have trillions of sensors, …” Michael R. Nelson, Director of Internet Technology and Strategy, IBM Number 100 Billion Sensors 10 Billion Mobile phones 1 Billion PCs Source: National Research Council USA 100 Million 1990 62 2000 Year 2010 2020

Last but not least: Digital Enterprise Research Institute Standardisation! 63 www. deri. ie

Digital Enterprise Research Institute 64 www. deri. ie