1 KR2002, Apr 2002 KR: Reinjecting Reality Mathematical ideas originate in empirics.. But, once they are so conceived, the subject begins to live a peculiar life of its own and is better compared to a creative one, governed almost entirely by aesthetical motivations …As a mathematical discipline travels, or after much abstract inbreeding, [it] is in danger of degeneration…whenever this stage is reached, the only remedy seems to me to be the rejuvenating return to the source; the reinjection of more or less directly empirical ideas --- John Von Neumann, 1953

The Semantic Web: KR’s Worst Nightmare? Professor James Hendler Co-Director, Maryland Information and Network Dynamics Laboratory

3 KR2002, Apr 2002 The nightmare: KR becomes relevant Artificial Intelligence researchers have studied such systems since long before the web was developed. 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.

4 KR2002, Apr 2002 Outline The SEMANTIC web The semantic WEB We’ve heard this kind of crap before, why should we believe this one? Challenges ahead But is it AI?

5 KR2002, Apr 2002 The SEMANTIC Web Event: title Event: date Event: Loc a photo:Photograph, Photo:File Photo:topic :event1#event:loc. Event1 a Event:event; Event:date “April 22-25,2002”, Event:Loc Event:Title “Eighth…”.

6 KR2002, Apr 2002 KR on the Web Many characteristics of the Web violate traditional KR assumptions!  It's Large and It Grows Fast  High Variety in Quality of Knowledge  Diversity of Content  Unknown/unpredictable Use Scenarios for the Knowledge  Problems of Trust, No Single Authority  Lack of Referential Integrity  Knowledge acquired, not engineered (Van Harmelen, 2000)

7 KR2002, Apr 2002 Web Semantics Semantic Web LayerCake (Berners-Lee, 99;Swartz-Hendler, 2001)

8 KR2002, Apr 2002 Putting semantics on the web

9 KR2002, Apr 2002 (and making it machine-readable)

Can’t we just use XML? This is what a web-page in natural language looks like for a machine

XML helps CV name education work private XML allows “meaningful tags” to be added to parts of the text

XML  machine accessible meaning CV name education work private But to your machine, the tags look like this….

Schemas take a step in the right direction Schemas help…. …by relating common terms between documents 

But other people use other schemas CV name education work private   >  Someone else has one like this….

The “semantics” isn’t there …which don’t fit in 

KR provides “external” referents to merge on SW languages add mappings And structure.       

17 KR2002, Apr 2002 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

18 KR2002, Apr 2002 The semantic WEB (Genome World - from Goble, 01) Goal: do to ontologies what the web does for documents

19 KR2002, Apr 2002 This leads to a radically new view of interoperation Distributed,partially mapped, inconsistent -- but very flexible! uses = some partial mapping

20 KR2002, Apr 2002 But, like the web…

21 KR2002, Apr 2002 Real examples Examples from Students violated every rule in the KR book  Extended existing ontologies Extended existing ontologies  Linked instances directly to terms from multiple ontologies Linked instances directly to terms from multiple ontologies  Mixed “real KR” and NL Mixed “real KR” and NL We can learn from their lessons 

22 KR2002, Apr 2002 But will it fly DAML+OIL is probably the most used AI language ever!!  Gaining acceptance by web players  Semantic Web Track being offered at WWW 2002  More people will attend WWW2002 Developer Day on SW than attend 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 US National Cancer Institute to publish cancer vocabulary in DAML+OIL Much New Startup activity (even in this economic climate) Many tools being developed  Many of them aimed at developers, not just AI literate types

23 KR2002, Apr 2002 W3C Web Ont WG Current Working Group includes over 50 members from 30+ organizations.  Industry including: Large companies such as Sun, IBM, HP, Intel, EDS, Fujitsu, Lucent, Nokia, Philips Electronics, Unisys, Daimler0Chrysler Newer/smaller companies such as 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  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 (From non-W3C members) Well-known KR researchers (Hayes, Stein) Tool Developers (Dean, Heflin) Domain experts (Borden)  W3C Team Connolly (HTML, XML. XML-schema); Brickley (RDF, RDF Core)

24 KR2002, Apr 2002 Moving to the futureof the web Semantic Web LayerCake (Berners-Lee, 99;Swartz-Hendler, 2001)

25 KR2002, Apr 2002 Web “travel agents” Query processed: 73 answers found  Google document search finds 235,312 possible page hits.  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...  The “UFO network” claims the “all cows in Texas have been replaced by aliens How many cows are there in Texas?

26 KR2002, Apr 2002 Web Agents need Service Descriptions

27 KR2002, Apr 2002 Services need Web Logics

28 KR2002, Apr 2002 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( “ u) Notice this one

29 KR2002, Apr 2002 Validation sites Buy into your favorite rule set  believable(x) :- claims(src,x) ^ accreditedbyChristianCoalition(src)  believable(x) :- claims(src,x) ^ linkfromMomsPage(src)  believable(x) :- claims(src,x) ^ accreditedby(“ ”, src) ^ Not-accreditedbyChristianColation(x)

30 KR2002, Apr 2002 AI But is it AI ? What about human intelligence  It's Large and It Grows Fast  Lack of Referential Integrity  High Variety in Quality of Knowledge  Diversity of Content  Unknown/unpredictable Use Scenarios for the Knowledge  Problems of Trust, No Single Authority  Knowledge acquired, not engineered Many characteristics of human intelligence violate traditional KR assumptions  It’s time for us to face up to the real challenge!!

31 KR2002, Apr 2002 Conclusion It is no longer a question of whether the semantic web could come into being, it can and will 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 KR community has lots to offer  If, and maybe only if, it is willing to revisit some basic assumptions The current environment is open, encouraging, moving fast, and exciting as heck  Come play!