Tools for the - PowerPoint PPT Presentation

Tools for the

Semantic web

Jim Hendler

http://www.mindswap.org

Knowledge representation, as this technology is often called, is currently in a state comparable to that of hypertext before the advent of the web: it is clearly a good idea, and some very nice demonstrations exist, but it has not yet changed the world. It contains the seeds of important applications, but to unleash its full power it must be linked into a single global system.

-- Tim Berners-Lee, inventor of the WWW, 2001.

Part I: Review of semantic WEB

Web page

Any Web Resource

<a href=

URI>

HTML

<a href=“http://…”>

On the Semantic WEB -- links are critical!

URI

URI

URI

RDF is like the web!

RDF

DOC1

<mind:Person rdf:id=“Hendler”>

<mind:title jobs:Professor>

<jobs:placeOfWork http://www.cs.umd.edu>

</mind:Person>

Mind:

Jobs:

Professor

DOC1

Mind:title

Hendler

Jobs:

Web Page

http://www…

Jobs:placeOfWork

XML is NOT semantics

XML is NOT semantics

<photo> <subject> http://www.w3.org/~timbl </subject> <name> Tim Berners-Lee</name> </name> …</photo>

XML is NOT semantics

Xml schema is DOCUMENT checking photo has multiple subject fields photo has one physical location etc.

<photo> <subject> http://www.w3.org/~timbl </subject> <name> Tim Berners-Lee</name> </name> …</photo>

XML is NOT semantics

Xml schema is DOCUMENT checking photo has multiple subject fields photo has one physical location etc.

WHICH SAYS NOTHING ABOUT TALKS, SUBJECTS, PEOPLE, EVENTS, etc.

<photo> <subject> http://www.w3.org/~timbl </subject> <name> Tim Berners-Lee</name> </name> …</photo>

The SEMANTICS is inthe links (e.g. to ontologies)!

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” …

<s:Class rdf:about="http://www.semanticweb.org/ontologies/swrc-onto-2000-09-10.daml#Conference">

<s:comment>

describes a generic conceptabout events

</s:comment>

<s:subClassOf rdf:resource="http://www.semanticweb.org/ontologies/swrc-onto-2000-09-10.daml#Event"/>

<a:disjointFrom rdf:resource="http://www.semanticweb.org/ontologies/swrc-onto-2000-09-10.daml#Workshop"/>

<a:restrictedBy rdf:resource="http://www.semanticweb.org/ontologies/swrc-onto-2000-09-10.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>

nme

CV

CV

work

vate

CV

educ

educ

• New SW languages add models to provide mappings and structure.
• XML necessary, not sufficient.

• Web ontologies, like the WWW itself, are not “separable”
• Thinking about the ontologies, without considering
• The links to other ontologies
• The instances that link to them
• The crawling and collecting of ontological terminologies

Is like thinking about the Web without the links!!

OtherProfessors

Othertitles

OtherPages

Mind:

Jobs:

Professor

OtherURIs

DOC1

Mind:title

Hendler

Jobs:

Web Page

http://www…

Jobs:placeOfWork

Otherdescriptions

OWL

Class, subclass

Property, subproperty

+ Restrictions

Range, domain

Local, global

Existential

Cardinality

+ Combinators

Union, Intersection

Complement

Symmetric, transitive

+ Mapping

Equivalence

Inverse

rdfs:Class rdf:ID="Meeting">

<rdfs:subClassOf>

<daml:Restriction>

<daml:onProperty rdf:resource="#MeetingName"/>

<daml:toClass rdf:resource="http://www.w3.org/2000/10/XMLSchema#string"/>

<daml:cardinality>1</daml:cardinality>

</daml:Restriction>

</rdfs:subClassOf>

<rdfs:subClassOf>

<daml:Restriction>

<daml:onProperty rdf:resource="#uri"/>

<daml:toClass rdf:resource="http://www.w3.org/2000/10/XMLSchema#uriReference"/>

<daml:maxCardinality>1</daml:maxCardinality>

</daml:Restriction>

</rdfs:subClassOf>

<rdfs:subClassOf>

<daml:Restriction>

<daml:onProperty rdf:resource="#location"/>

<daml:toClass rdf:resource="http://www.w3.org/2000/10/XMLSchema#string"/>

<daml:cardinality>1</daml:cardinality>

</daml:Restriction>

<rdfs:subClassOf>

<daml:Restriction>

<daml:onProperty rdf:resource="#Issues" />

<daml:toClass rdf:resource="#Issue" />

<daml:minCardinality>0</daml:minCardinality>

</daml:Restriction>

</rdfs:subClassOf>

</rdfs:Class>

• In science, models provide interoperability across jargons
• Mathematical models: equations of a system
• Physical models: “sticks and balls” of the atom
• Virtual models: the visualization of a complex data set
• INFORMATION MODELS: taxonomies and thesauris
• Ontologies extend thesaurus information models to provide
• Semantic restrictions on property relations
• Must have vs. May have vs. Doesn’t have
• Has some vs. has N vs. has 1
• Some vs. All property restrictions
• Formal underpinnings
• Logical entailments
• Note: rules, logics, proofs are parts of ontologies, but not yet at a “consensus” level for standardization
• Should build as add-ons to OWL to take advantage of “terminology features”

• OWL is NOT…
• … A knowledge representation language per se
• Definitely not “The standard: for KR”
• … A “Description Logic” per se
• It does support DL “idioms”
• E.g. “Lymphoma” is restricted to be a subClassOf those things whose “disease” property is “Cancer”
• It will include a “subset” which is
• Complete, decidable, in DL complexity case
• But, it will allow uses that DLs do not
• Maybe outside the “semantics” of the model theory
• …The right thing to use in KR/KA research per se
• But do use it to distribute your results
• But do use it to test your theories

• OWL is
• WEB-BASED
• DISTRIBUTED
• MACHINE-PROCESSIBLE
• BASED ON DAML+OIL
• By charter!
• It may become a Web recommendation
• Same “language status” as HTML, XML, XML schema
• A starting place for further evolution
• And SMIL, P3P,
• Standard ≠ Use

• The good news:
• DAML+OIL is already the most used ontology language in history
• Sept 30, 02: Crawler finds 5M+ DAML statements on 20,000+ web pages
• Doesn’t include many instance KBs tied to ontologies
• Doesn’t include many very large RDFS-based KBs that include some OWL
• OWL is being supported by large corporation labs
• Web tool developers: IBM, HP, Sun, Intel, Fujitsu
• Content providers: Daimler-Chrysler, Nokia, Motorola, EDS, Agfa
• OWL is starting to be used by thesaurus distributors
• C.f. National Cancer Institute metathesaurus to be released in OWL
• The bad news
• On the web it is a statistical blip -- the web is HUGE (HUMONGOUS!!)
• The big players are still on the sidelines
• We could become the next XML or the next SMIL

• Tom Mitchell made an interesting point
• He says “users are lazy” they won’t do mark-up
• He says we should use NLP + machine learning (primarily)
• He’s WRONG
• Greatest impact likely to be non-textual, non-document content

• There are not now, and never will be, enough knowledge engineers to support the important, critical applications of our technology
• Government applications: NASA, US DoD …
• Health Care applications: Open Health, Swiss hospitals …
• Genomics/Bioinformatics: NCI metathesaurus, Gene Ontology…
• ...
• Historians: Freedman’s project
• Let alone the really important stuff out there
• MY information
• My photo archives, my home page, my daughter’s home page, my project pages, my favorite hobby pages, etc. etc. etc.

Personal information created the Web!!!

• Tools must consider work v. value
• People will NOT use tools that require a lot of work and have little (perceived) value
• People WILL use tools that save them work and/or provide high (perceived) value
• “Perceived” value ≠ “real” value in many cases
• Creating Web pages (ca. 1993) was “cool”
• No study has yet shown a positive work value for the Web as a whole
• But it has changed the way we live
• Viral: My friend sees it, wants one. My competitor sees it, needs one

TBL’s “secret” advice: Start small but viral and you can change many things (July, 02)

Ont

Library

Tell me about your : Important Person Hobby Job

Marked Up Pages

Query

I know about - Scuba shop - Scuba vacation 1 - Scuba vacation 2 - Scuba instructor

classes

Choice

XHTML+OWL

• Many people don’t have home pagesValue: Hints for useful properties (using ontology classes)Help create content (using ontology instances).
• Note: Useful libraries (lots of stuff) already exist (see daml.org)

KB

• Combine browsing, search, and authoringValue: As I link to concepts, I find useful resourcesPages, Databases, programs, etc.

Buy the French version of a book from amazon.fr and have it sent to my mother

• Virtually no one will create ontologies from scratch
• High-End ontology developers will be a tiny percentage (10,000 High end Web Designers = 1/10,000 of users)
• It is easier to read then to create ontologies
• Expect “cut and paste” (HTML analogy)
• Most used OWL editor to date is Emacs
• Can Bootstrap from existing content
• HTML screen scrapers, structured data, Excel spread sheets,…
• No training allowed
• Motivated users will skim the docs on occasion
• Most users want to use it now
• “Everyone” has a browser - deploy tools through that
• Common metaphors must be used: Form fill, menu, search

Note: No formal justification for any of these - but it worked before!

• Tools can be domain independent
• Your tool should be usable in lots of contexts!
• Use the standards:
• OWL and its successors crucial
• Tools should assume multiple ontologies
• “It’s the links, stupid”
• Ontology search, collection, “integration” crucial
• Check out the DAML crawler (http://www.daml.org/crawler)
• BackEnd technologies must be scaleable
• Can co-evolve with Semantic Web size
• But remember, the Web is HUGE

• Users MUST be able to add their own concepts
• Semantic Web (and OWL) allow this
• Advanced users will become ontology providers
• It will be “cool” to have yours be the ontology of choice in a domain
• Consistency CANNOT be maintained on the web
• May be a useful heuristic
• Insist on consistency and the Semantic Web fails!

• There is, and will be, no market for any of this unless we create it!
• No one will make money selling their tools until we have MANY more users
• Make small, cheap, easy to download version of your tools available
• Give it away
• The big winners on the web made it available for free:
• Browsers: Mosaic, Netscape, IE
• Plug-ins: Flash, RealPlayer, Quicktime
• Tools: Adobe, Real Media

Maryland Information and Network Dynamics Laboratory

Semantic Web Agents Project

http://www.mindswap.org/

• Open source Tools at http://www.mindswap.org
• Described in proceedings
• But out of date - open source moves fast
• Based on the principals outlined in this talk
• RIC: Ontologies make it EASIER to enter knowledge
• Turn properties into forms, use restrictions to check form filling
• Creates a KB of the results that can be used for search
• Coming soon: create a nice web page (using SXMLT)
• SMORE: Create content and markup as you go
• Multiple ontology
• ConvertToRDF: Dump spreadsheets to RDF using mapping ontology
• RDFScreenScraper: turn semi-structured web pages into
• ParkaSW: Scaleable, data-based KB back-end
• Some built in inferencing
• Pulled from the patent system to become open source!

• The Semantic Web is real, and it is moving fast
• Two years ago you hadn’t heard of it, now it’s on the cover of your proceedings
• We’ll win if we remember the “rules of the web”
• Berners-Lee Principle: Build small but viral
• Hendler’s Rule: On the web there is no “THE”
• Yours is ONE of the ways of doing it
• Consensus is hard, but critical
• We did it once and createdDAML+OIL, the most-used AI language ever
• Everyone’s application is needed
• Value proposition: Make it fun, cool, and useful and people will kill to do the markup (The Web proves this)
• Give it away: Create the markets and we’ll all win
• YOUR work is important!
• This time it could be for real!

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