Introducing the Semantic Web
Professor James Hendler
http://www.cs.umd.edu/~hendler
Co-Director, Maryland Information and Network Dynamics
Laboratory
Semantic Web Agents Project
http://www.mindswap.org
The Evolving Web
Web of
Knowledge
Proof, Logic and
Ontology Languages
DATA/PROGRAMS
Shared terms/terminology
Machine-Machine communication
2010
Resource Description Framework
eXtensible Markup Language
HyperText Markup Language
HyperText Transfer Protocol
Self-Describing Documents
2000
DOCUMENTS
Foundation of the Current Web
1990
J. Hendler, 2002
Berners-Lee, Hendler; Nature, 2001
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Web Semantics
Semantic Web LayerCake (Berners-Lee, 99;Swartz-Hendler, 2001)
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Can’t we just use XML?
This is what a web-page in natural language
looks like for a machine
XML helps
XML allows “meaningful tags” to be added to
parts of the text
< name >
< education>
< CV >
< work>
< private >
XML  machine accessible meaning
But to your machine,
the tags look like this….
name >
< name
<education>
< education>
< CV
CV >
<work>
< work>
<private>
< private >
Schemas take a step in the right direction
Schemas help….
< CV >
private
…by relating
common terms
between documents
But other people use other schemas
Someone else has one like this….
<name>
name >
<<educ>
education>
<> >
< work
<<>
private >
CV> >
<<CV
The “semantics” isn’t there
< CV >
private
…which don’t fit in
KR provides “external” referents to merge on
nme
CV
CV
work
vate
educ
CV
ed
uc
<name
< name >>
<<educ
education> >
SW languages add mappings
And structure.
<> >
< work
<<
private>>
<< CV
CV >
Which is what the web was meant to be!!

"This is a pity, as in fact documents on the web describe real objects and imaginary concepts, and
give particular relationships between them... For example, a document might describe a person.
The title document to a house describes a house and also the ownership relation with a person. ...
This means that machines, as well as people operating on the web of information, can do real
things. For example, a program could search for a house and negotiate transfer of ownership of
the house to a new owner. The land registry guarantees that the title actually represents reality.”
 Tim Berners-Lee plenary presentation at WWW Geneva, 1994
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Putting semantics on the web
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(and making it machine-readable)
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Event:title
<daml:ObjectProperty rdf:ID="photograph">
<rdfs:domain rdf:resource="#Picture"/>
<rdfs:range rdf:resource= …#person"/>
</daml:ObjectProperty>
Event:WebPage
< > rdf:type photo:Photograph,
Photo:File http://…/images#image1,
Photo:topic :event1#event:speaker.
Event1 a Event:event;
date “May 7-11”,
speaker http://…#timbl.html
Title “WWW 2002…”
TimBL rdf:type w3c-ont:person;
name “Tim Berners-Lee”
…
J. Hendler, 2002
<s:Class
rdf:about="http://www.semanticweb.org/o
ntologies/swrc-onto-2000-0910.daml#Conference">
<s:comment>
describes a generic conceptabout events
</s:comment>
<s:subClassOf
rdf:resource="http://www.semanticweb.or
g/ontologies/swrc-onto-2000-0910.daml#Event"/>
<a:disjointFrom
rdf:resource="http://www.semanticweb.or
g/ontologies/swrc-onto-2000-0910.daml#Workshop"/>
<a:restrictedBy
rdf:resource="http://www.semanticweb.or
g/ontologies/swrc-onto-2000-0910.daml#genid18"/>
<rdf:Description rdf:about="http://www.w3.org/2001/03/earl/0.95#Person">
<rdf:type rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
<rdfs:subClassOf rdf:resource="http://www.w3.org/2001/03/earl/0.95#Assertor"/>
</rdf:Description>
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On the Web -- links are critical!
Web page
Any Web Resource
<a href=
URI>
HTML
<a href=“http://…”>
On the Semantic WEB -- links are critical!
URI
URI
RDF
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URI
RDF is like the web! And…
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RDF graphs resemble semantic nets
DOC1
<mind:Person rdf:id=“Hendler”>
<mind:title jobs:Professor>
<jobs:placeOfWork http://www.cs.umd.edu>
</mind:Person>
Jobs: Professor
Mind:
Mind:title
DOC1
Jobs:
J. Hendler, 2002
Hendler
Jobs:placeOfWork
Web Page
http://www…
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Semantics on the WEB
 RDF, like the WWW itself, is not “separable”
 Thinking about the ontologies, without considering
 The links to other terms
 The instances that link to them
 The crawling and collecting of ontological terminologues
Is like thinking about the Web without the links!!
Other
titles
Mind:
Other
URIs
Jobs:
J. Hendler, 2002
Other
Professors
Jobs: Professor
Mind:title
DOC1
Other
Pages
Hendler
Jobs:placeOfWork
Other
descriptions
Web Page
http://www…
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Radically new view of Semantics
= some partial mapping
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
uses
Distributed,partially
mapped,
inconsistent -- but SCALEABLE!
uses
uses
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Real examples
 Examples from
http://dormouse.cs.umd.edu:8080/wiki/cmsc498wiki.wiki
 Students violated every rule in the KR book



Extended existing ontologies
Linked instances directly to terms from multiple ontologies
Mixed “real KR” and NL
 We can learn from their lessons

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http://dormouse.cs.umd.edu:8080/wiki/assignment1_collected_les.wiki
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Current Activities
You
are
here
Semantic Web LayerCake (Berners-Lee, 99;Swartz-Hendler, 2001)
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W3C Web Ontology Working Group
 Web Ontology Working Group in the W3C Semantic Web Activity
aimed at “extending the semantic reach of current XML and RDF
meta-data efforts. “
 History





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DAML+OIL is submitted as a joint committee effort published as a W3C note .
W3C WG Announcement in November 2001 http://lists.w3.org/Archives/Public/www-rdf-logic/2001Nov/0000.html
Weekly teleconferences started in November 2001
First Face to Face Meeting - New Jersey (Lucent), Jan ‘02; 2nd - Amsterdam
April (W3C); 3rd - CA (Fujitsu/Stanford host) July; 4th in Bristol UK (HP Host)
Oct.
Four Working Drafts to date
 Requirements/Use cases - March 2002
 3 Technical Documents - July 2002 (Language renamed OWL)
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Membership
 Current Working Group includes over 50 members from over 30 organizations.

Chairs
 J. Hendler, MIND Lab UMCP
 G. Schreiber, Univ. of Amsterdam

Industry including:
 Large companies - Daimler Chrysler, IBM, HP, Intel, EDS, Fujitsu, Lucent, Motorola, Nokia,
Philips Electronics, Sun, Unisys
 Newer/smaller companies - IVIS Group, Network Inference, Stilo Technology, Unicorn
Solutions

Government and Not-For-Profits:
 US Defense Information Systems Agency, Interoperability Technology Association for
Information Processing, Japan (INTAP) , Electricite De France, Mitre, NIST

Universities and Research Centers:
 University of Bristol, University of Maryland, University of Southamptom, Stanford
University
 DFKI (German Research Center for Artificial Intelligence), Forschungszentrum Informatik,
Ontoweb

Invited Experts
 Well-known academics from non-W3C members (Hayes, Heflin, Stein, Borden)
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But will it fly?
 DAML+OIL is already the most used ontology language ever!!

http://www.daml.org (3.5M statements on 25,000 web pages)
 Gaining acceptance by web players


Semantic Web Track being offered at WWW 2002
3x more people attended WWW2002 Developer Day on SW than attended KR
 Significant (international) Govt Support

US DARPA/NSF; EU IST Framework 5,6

Japan, Germany, Australia considering significant investments
US National Cancer Institute to publish cancer vocabulary in DAML+OIL

 Much New Startup activity (even in this economic climate)
 Many tools being developed

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Many of them aimed at developers, not just AI literate types
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Making Markup Easier
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Machine worries about the syntax
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Use that markup in query/portal interfaces
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Extending ontologies on the fly
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Semantic Web Portals:
The Mosaic of the semantic web?
<XSLT/>
<Oncogene rdf:ID="Oncogene,
MYB"><code>C3682</code><id>3683</id>
<Found_In_Organism
rdf:ID="Human"></Found_In_Organism>
<Gene_Has_Function rdf:ID="Gene
Transcription"></Gene_Has_Function>
<Gene_Has_Function
rdf:ID="Transcriptional
Regulation"></Gene_Has_Function>
<In_Chromosomal_Location rdf:ID="6q22q23"/>
</Oncogene>
J. Hendler, 2002
<Oncogene rdf:ID="Oncogene NMYC">
<code>C17656</code><id>17657</id><Found_In_Organism
rdf:ID="Human"></Found_In_Organism>
<In_Chromosomal_Location rdf:ID="2p24.1"/>
<Gene_Has_Function rdf:ID="Transcriptional Regulation">
</Gene_Has_Function><Gene_Associated_With_Disease
rdf:ID="Neuroblastoma">
</Gene_Associated_With_Disease></Oncogene>
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Moving to the futureof the web
Semantic Web LayerCake (Berners-Lee, 99;Swartz-Hendler, 2001)
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Web “travel agents”
How many cows are there in Texas?
Query processed: 73 answers found

Google document search finds 235,312 possible page hits.

Http://www…/CowTexas.html claims the answer is 289,921,836

A database entitled “Texas Cattle Association” can be queried for the
answer, but you will need “authorization as a state employee.”

A computer program that can compute that number is offered by the State of
Texas Cattleman’s Cooperative, click here to run program.
...
The “sex network” can answer anything that troubles you, click here for
relief...



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The “UFO network” claims the “all cows in Texas have been replaced by
aliens
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Allows new capabilities
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Services off the desktop
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Or perhaps on different desktops…
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Web Agents need Service
Descriptions
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Semantic Web Service Description
- <daml:Class rdf:ID="CreateAcct">
<rdfs:subClassOf
rdf:resource="http://www.daml.org/services/damls/2001 /10/Process.daml#AtomicProcess" />
- <rdfs:subClassOf>
- <daml:Restriction daml: cardinality="1">
<daml:onProperty rdf:resource="#createAcctInfo" />
</ daml:Restriction>
</ rdfs:subClassOf>
- <rdfs:subClassOf>
- <daml:Restriction daml: cardinality="1">
<daml:onProperty rdf:resource="#createAcctOutput" />
</ daml:Restriction>
</ rdfs:subClassOf>
</ daml:Class>
- <rdf:Property rdf:ID="createAcctInf o">
<rdfs:subPropertyOf
rdf:resource="http://www.daml.org/services/damls/2001 /10/Process.daml#input" />
<rdfs:domai n rdf:resource="#CreateAcct" />
<rdfs:range rdf:resource="#AcctInf o" />
</ rdf:Property>
- <rdf:Property rdf:ID="createAcctOutput">
<rdfs:subPropertyOf
rdf:resource="http://www.daml.org/services/damls/2001 /10/Process.daml#output" />
<rdfs:domai n rdf:resource="#CreateAcct" />
<rdfs:range rdf:resource="#CreateAcctOutputType" />
</ rdf:Property>
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Use Semantics for Composition
Translate my symptoms from
French and find me a pharmacy
that has the necessary medicine
(then compute how to get there
and print the directions)
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Print the directions to a pharmacy
which has a medicine that cures
the symptoms that I will tell you
(in French)
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Or, translate to Planning Operators
- <daml:Class rdf:ID="DeliveryType">
- <daml:oneOf rdf:parseType="daml:collection">
Ź <DeliveryType rdf:ID="FedExOneDay" />
Ź <DeliveryType rdf:ID="FedEx2-3day" />
Ź <DeliveryType rdf:ID="UPS" />
Ź <DeliveryType rdf:ID="Ordin aryMail" />
Ź </ daml:oneOf>
Ź </ daml:Class>
The atomic process SpecifyDeliveryD etailsΣ can be transla ted into a SH OP2 operator
with cor responding pr econd itions as follows:
(:operator (!SpecifyDeliveryDetails ?deli veryAddress ?pa ckagingSelection
?deliveryTypeSelection)
((not (same ?deliveryAdd ress ni l))
(not (same ?packagingSelection nil))
(not (same ?deli veryTypeSelection nil))
(eval (stringp ?del iveryAdd ress))
(eval (member ‘?packagingSelection ‘(Gif twrap Ordinary)))
(eval (member ‘?deliveryTypeSelection ‘(FedExOneDay FedEx23day UPS OrdinaryMail))))
()
())
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For goal-based service composition
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Buy the French version of a book from amazon.fr and
have it sent to Mom’s address
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Services need Web Logics
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Web of Trust
 Claims can be verified if there is supporting evidence from
another (trusted) source
 We only believe that someone is a professor at a university if
the university also claims that person is a professor, and the
university is on a list I trust.
believe(c1) :- claims(x, c1) ^ predicate(c1, professorAt) ^
arg1(c1, x) ^ arg2(c1, y) ^ claims(c2, y) ^
predicate(c2, professorAt) ^ arg1(c2, x) ^
arg2(c2, y) ^ AccreditedUniversity(y)
AcknowledgedUniversity(u) :- link-from(“http://www.cs.umd.edu/university-list”,u)
Notice this one
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Distributed Trust
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Conclusion
 It is no longer a question of whether the semantic web will
come into being, it is already here!
 We’re already well past the starting gate



Web ontologies, term languages, “shims” to DB and services, research in
proofs/rules/trust
Standardization providing a common denominator for KR researchers as
well as web developers
Small companies starting to form, Big companies starting to move
 The current environment is open, encouraging, moving fast,
and exciting as heck

Come play!
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