o n t o p e d i a the identity of everything topic maps and the semantic web
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O N T O P E D I AThe Identity of Everything
Topic Maps and theSemantic Web
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O N T O P E D I AThe Identity of Everything
Semantic Web – The “Layer Cake”
Tim Berners-Lee Keynote Speech in 2005
XML
How the two families stack up
Topic MapsRDF
TMCL
RDF Schema
OWL
CTM RDF/XML N3XTM RDF/A
ISOSeamless Knowledge
W3CSemantic Web
LTMT
MQ
L
SP
RQ
L
OR
GS
YN
TA
XM
OD
EL
CO
NS
TR
AIN
TS
QU
ER
Y
OR
GS
YN
TA
XM
OD
EL
RE
AS
ON
ING
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O N T O P E D I AThe Identity of Everything
Topic Maps and the Semantic Web
Some people think RDF/OWL andTopic Maps are competitors– I do not think this is not true– I think they complement each other
The Semantic Web gets muchmore publicity1. W3C can bask in the glamour of the Web
2. RDF and OWL appealed immediately to academics
But why do people think they compete?1. RDF/OWL and Topic Maps have a number of similarities
2. They stem from rival organizations (W3C and ISO)
3. There are a few bigots
4. Most people do not understand the difference...
RDF/OWL
Topic Maps
Romeo and Juliet
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O N T O P E D I AThe Identity of Everything
The are superficial similarities
Both “extend” XML into the realm of semantics
Both allow assertions to be made about things in the real world
Both define abstract, associative (graph-based) models
Both have URI-based models of identity
Both allow forms of inferencing or reasoning
Both have XML-based interchange syntaxes
Both have constraint languages and query languages
But they are also different in some crucial respects...
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O N T O P E D I AThe Identity of Everything
But the differences are significant
Different roots– Topic Maps has its roots in traditional finding aids (indexes, thesauri, etc.)
– RDF/OWL has its roots in document metadata and formal logic
Different levels of semantics…– RDF is more low level
– Topic Maps has more higher-level semantics
Different models– Identity, scope, association roles, n-ary relationships, variant names, …
Different goals– RDF: An artificially intelligent web for software agents
– Topic Maps: Findability and knowledge integration for humans
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O N T O P E D I AThe Identity of Everything
The Most Crucial Differences
RDF/OWL is for machines; Topic Maps is for humans.
RDF/OWL is optimized for inferencing; Topic Maps is optimized for findability.
RDF/OWL is based on formal logic; Topic Maps is not based on formal logic.
RDF/OWL is to mathematics asTopic Maps is to language.
RDF/OWL is to Aristotle asTopic Maps is to Wittgenstein.
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O N T O P E D I AThe Identity of Everything
What is this supposed to be?
Is it an H or an A?
T E C T
H H A A
The moral is: Fuzziness is a fact. Humans can handle it; machines can’t.
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O N T O P E D I AThe Identity of Everything
Different capabilities
RDF/OWL, to support logic-based inferencing,cannot allow fuzziness
– Topic Maps, because it is for humans,has to support fuzziness
OWL ontologies tend to be very stringent and complex– Topic Maps ontologies tend to be simple and less formal
OWL has properties for things that Topic Maps doesn’t need– Some Topic Maps features would be too complex for OWL
In short, they are optimized for different purposes...
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O N T O P E D I AThe Identity of Everything
RDF or Topic Maps?
Do you simply want to encode document metadata?– RDF is ideal and you won’t need OWL
Do you want to achieve subject-based classification of content?– Topic Maps provides the best combination of flexibility and user-friendliness
Do you want both metadata and subject-based classification?– Go straight for Topic Maps because it also supports metadata
Do you want to develop agent-based applications?– Use RDF/OWL ... but if you already have Topic Maps, you’re half way there
Most importantly, whatever you choose, you can always move your data
between RDF and Topic Maps, thanks to the RDFTM work…
RDF is more low-level; oriented towards machines Topic Maps is more high-level; oriented towards humans OWL is oriented towards artificial intelligence
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O N T O P E D I AThe Identity of Everything
RDFTM: Data interoperability
RDF/Topic Maps Interoperability Task Force– A task force within the Semantic Web Best Practices
and Deployment Working Group
Chartered to deliver two documents:– Survey of Existing Interoperability Proposals
– Guidlines for RDF/Topic Maps Interoperability
Survey published in February 2006– http://www.w3.org/TR/rdftm-survey/
Draft guidelines published in June 2006– http://www.w3.org/2001/sw/BestPractices/RDFTM/guidelines-20060630.html
– The task force is now disbanded and the work will be finalized by ISO
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O N T O P E D I AThe Identity of Everything
Topic Maps andHypertext
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O N T O P E D I AThe Identity of Everything
Tim Berners-Lee1989
Information Management: A Proposal
World Wide Web
Bill Atkinson1987
HyperCard
Vannevar Bush and Hypertext
Vannevar Bush1945
As We May ThinkMemex
Doug Engelbart1962
Augmenting Human IntellectNLS / AUGMENT
Ted Nelson1965
“Hypertext”Xanadu
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O N T O P E D I AThe Identity of Everything
“As We May Think”
Concerned with the problem of finding information
– Existing technology hopelessly out of date:
– The amount of information is being “expanded at a prodigious rate”, but the means we use to find it is “the same as was used in the days of square-rigged ships”
– The solution is to get away from hierarchical systems of organization and adopt new techniques that reflect how the brain works
Vannevar Bush1945
As We May ThinkMEMEX
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O N T O P E D I AThe Identity of Everything
Associative thinking
“The human mind … operates by association.
With one item in its grasp, it snaps instantly to the
next that is suggested by the association of
thoughts, in accordance with some intricate web
of trails carried by the cells of the brain… The
speed of action, the intricacy of trails, the detail of
mental pictures, is awe-inspiring beyond all else in
nature.”
Vannevar Bush: As We May Think (1945)
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O N T O P E D I AThe Identity of Everything
Memex (memory extender)
A “sort of mechanized private file and library”
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O N T O P E D I AThe Identity of Everything
Memex (memory extender)
Consists of a desk containing– a very large set of documents stored on microfilm– screens on which those documents are projected– a device for photographing new documents– a mechanism for retrieving documents at the push of a button– the ability to create links between documents– the ability to build trails through documents, add comments to
documents, insert new documents, etc.
Note how everything revolves around documents
Consists of a desk containing– a very large set of documents stored on microfilm– screens on which those documents are projected– a device for photographing new documents– a mechanism for retrieving documents at the push of a button– the ability to create links between documents– the ability to build trails through documents, add comments to
documents, insert new documents, etc.
Note how everything revolves around documents
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O N T O P E D I AThe Identity of Everything
Is this how you think?
Is your head full of little documents all hyperlinked together?
I doubt it ! Mine certainly isn’t ! We don’t think in
terms of hyperlinked documents; we think in terms of concepts, and associations between concepts?
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O N T O P E D I AThe Identity of Everything
Bush
MEMEX
As We May Think
Engelbart
Nelson
Berners-Lee
WWW
Hypertext
Xanadu
AUGMENT
NLS
How we really think
Documents are about subjects Those subjects exist as concepts in our brains They are connected by a network of associations This is how we store knowledge Documents are just a representation of some part
of that knowledge
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O N T O P E D I AThe Identity of Everything
Bush – right and wrong
Vannevar Bush was right that people think associatively
He was right that organizing information in this way would make it easier to find
But he was wrong in adopting a document-centric approach to the problem
His basic idea – organize information “as we may way think” – was a great inspiration to Engelbart, Nelson, Atkinson, and Berners-Lee
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O N T O P E D I AThe Identity of Everything
Barking up the wrong tree
But the Memex sent them all off in the wrong direction Hypertext has been barking up the wrong tree ever since
And the Web, magnificent as it is, has made things “worse”
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O N T O P E D I AThe Identity of Everything
“As We May Think”
Concerned with the problem of finding information
– Existing technology hopelessly out of date:
– The amount of information is being “expanded at a prodigious rate”, but the means we use to find it is “the same as was used in the days of square-rigged ships”
– The solution is still to get away from hierarchical systems of organization and adopt new techniques that reflect how the brain works
– That solution has to be subject-centric, not document-centric like the Web
Vannevar Bush1945
As We May ThinkMEMEX
card catalogs
(63 years on)
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O N T O P E D I AThe Identity of Everything
Which brings us to Topic Maps
What’s special about it?– #1 The TAO* model corresponds to how people think
Bush
MEMEX
As We May Think
Engelbart
Nelson
Berners-Lee
WWW
Hypertext
Xanadu
AUGMENT
NLS
Puccini
Tosca
Lucca
composed by
born in
composed by
MadameButterfly
knowledge layer
information layer
* Topics + Associations + Occurrences
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O N T O P E D I AThe Identity of Everything
Subject-centric computing– a broader perspective
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O N T O P E D I AThe Identity of Everything
Topic Maps as a paradigm shift
Topic Maps started out as a way to merge indexes It turned into a knowledge representation formalism But its significance is far greater
Now the flag-bearer for subject-centric computing A paradigm shift in how we use computers
Cf. object-oriented programming... ...and Copernicus
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O N T O P E D I AThe Identity of Everything
Object-oriented programming
Response to 1960’s software crisis– Computer programs more and more complex
– Difficult to maintain software quality
Code simulates the world (as perceived by a human)– Objects represent real-world concepts (cf. topics)
– They are grouped into classes (cf. topic types)
– Data structures capture relationships between objects(cf. associations)
Represented a paradigm shift in programming– OO languages now near universal (Java, C#, Ruby, Python, ...)
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O N T O P E D I AThe Identity of Everything
(Actually some Greek, Indian and Muslim scholars knew better, but the view of Aristotle, Ptolemy and the Christian Church was dominant)
The heliocentric revolution
For 1,000s of years people thought that the sun revolved around the earth
In 1543 Copernicus changed all that
His heliocentric theory turned our understanding of the universe inside out.
This was another paradigm shift
Sun
Earth
Sun
Earth
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O N T O P E D I AThe Identity of Everything
Subject-centric computing
Today we face a similar situation in computing and information management
Computers are at the centre of our information universe
Applications and documents revolve around them
The subjects we’re really interested in are nowhere to be seen
Or at least, nowhere to be found
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O N T O P E D I AThe Identity of Everything
Computing “as we may think”
This is wrong, because it does not reflect how humans think
Humans think in terms of subjects, concepts, ideas
We must put subjects at the centre, because that’s what we’re really interested in
This is the essence ofsubject-centric computing
It really is a paradigm shift –
Topic Maps is showing the way
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O N T O P E D I AThe Identity of Everything
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O N T O P E D I AThe Identity of Everything
topic maps
tm2008
bantu semantics
LING 2110
INF 2820rana
keynote
OOXML
K185gambia
opera
janacek
bayreuthhåkon
TM2008
Topic page
EmailsDocumentsWeb pages
Copy PSIΨ
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O N T O P E D I AThe Identity of Everything
Subject-centric file system
The file system is a hierarchy and that’s a pain– Trees aren’t expressive enough
WinFS looked like it might change all that– New data storage and management system announced in 2003
– Didn’t make it into Vista. Seems to have disappeared
Let the new file system be a topic map!– “Folders” are topics with global identifiers
– User-defined metadata on “folders” (internal occurrences)
– External occurrences
– Related through navigable, typed associations
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O N T O P E D I AThe Identity of Everything
Subject-centric operating system
Now that the file system is a topic map, why not go the whole hog?
– Services to applications for assigning PSIs
– NLP based help for (semi-automatically) categorizing documents
– Ability to extract fragments from the system topic map
– Peer-to-peer features for exchanging fragments with others
– Facilities for context-based virtual merges under user control
– ...