1KR2002, 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 Hendlerhttp://www.cs.umd.edu/~hendler

Co-Director, Maryland Information and Network Dynamics Laboratory

3KR2002, 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.

4KR2002, Apr 2002

Outline

The SEMANTIC webThe semantic WEBWe’ve heard this kind of crap before, why

should we believe this one?Challenges aheadBut is it AI?

5KR2002, Apr 2002

The SEMANTIC Web

Event:title

Event:date

Event:Loc

< > a photo:Photograph, Photo:File http://…/images#image1, Photo:topic :event1#event:loc.

Event1 a Event:event; Event:date “April 22-25,2002”, Event:Loc http://…/Toulouse, Event:Title “Eighth…”.

6KR2002, 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)

7KR2002, Apr 2002

Web Semantics

Semantic Web LayerCake (Berners-Lee, 99;Swartz-Hendler, 2001)

8KR2002, Apr 2002

Putting semantics on the web

9KR2002, 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 toparts 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….

CV

name

education

work

private

< >

< >

< >

< >

< >

< >

<>

<>

<>

<>

CV

name

education

work

private

< >

< >

< >

< >

< >

< >

<>

<>

<>

<>

< > …by relating common termsbetween documents

But other people use other schemas

CV

name

education

work

private

< >

< >

< >

< >

< >

< >

>

<>

<>

Someone else has one like this….

The “semantics” isn’t there

CV

name

education

work

private

< >

< >

< >

< >

< >

< >

<>

<>

<>

<>

CV

name

education

work

private

< >

< >

< >

< >

< >

< >

<>

<>

<>

<>

< >

…which don’t fit in

CV

name

education

work

private

< >

< >

< >

< >

< >

< CV >

<name >

<educ >

<>

<⇐∨ >

KR provides “external” referents to merge on

CV

name

education

work

private

< >

< >

< >

< >

< >

< >

<>

<>

<>

<>

CV

name

education

work

private

< >

< >

< >

< >

< >

< >

<>

<>

<>

<>

CV

name

education

work

private

< >

< >

< >

< >

< >

< >

<>

<>

<>

<>

SW languages add mappingsAnd structure.

CV

name

education

work

private

< >

< >

< >

< >

< >

< CV >

<name >

<educ >

<>

<⇐∨ >

CV

name

education

work

private

< >

< >

< >

< >

< >

< CV >

<name >

<educ >

<>

<⇐∨ >

CV

name

education

work

private

< >

< >

< >

< >

< >

< CV >

<name >

<educ >

<>

<⇐∨ >

CV

name

education

work

private

< >

< >

< >

< >

< >

< CV >

<name >

<educ >

<>

<⇐∨ >

CV

name

education

work

private

< >

< >

< >

< >

< >

< CV >

<name >

<educ >

<>

<⇐∨ >

17KR2002, 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

18KR2002, Apr 2002

The semantic WEB

StructuralGenomics

Population Genetics

Genome sequence

Functionalgenomics Tissue

Clinical trial

Disease

Clinical Data

(Genome World - from Goble, 01)

Goal: do to ontologies what the web does for documents

19KR2002, Apr 2002

This leads to a radically new view of interoperation

Distributed,partially mapped, inconsistent -- but very flexible!

uses

uses

uses

uses

usesuses

uses

uses

uses

uses

uses

uses

usesuses

uses

uses

uses

uses

uses

uses

usesuses

uses

uses

uses

uses

uses

uses

usesuses

uses

uses

uses

uses

uses

uses

usesuses

uses

uses

uses

uses

uses

uses

usesuses

uses

uses

= some partial mapping

20KR2002, Apr 2002

But, like the web…

21KR2002, Apr 2002

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 http://dormouse.cs.umd.edu:8080/wiki/assignment1_collected_les.wiki

22KR2002, Apr 2002

But will it fly

DAML+OIL is probably the most used AI language ever!! http://www.daml.org

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

Much New Startup activity (even in this economic climate) Many tools being developed

Many of them aimed at developers, not just AI literate types

23KR2002, 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)

24KR2002, Apr 2002

Moving to the futureof the web

Semantic Web LayerCake (Berners-Lee, 99;Swartz-Hendler, 2001)

25KR2002, Apr 2002

Web “travel agents”

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... The “UFO network” claims the “all cows in Texas have been replaced by

aliens

How many cows are there in Texas?

26KR2002, Apr 2002

Web Agents need Service Descriptions

27KR2002, Apr 2002

Services need Web Logics

28KR2002, 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(“http://www.cs.umd.edu/university-list”,u)

Notice this one

29KR2002, 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(“http://foo.com/Unabomber/Friends/rules”,src) ^ Not-accreditedbyChristianColation(x)

30KR2002, Apr 2002

But is it AI 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!!

31KR2002, 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!