Download - The Knowledge Cartography – A New Approach to Reasoning over Description Logics Ontologies
January 21-27, 2006, Měřín, Czech Republic
The Knowledge Cartography –A New Approach to Reasoning
over Description Logics Ontologies
Krzysztof Goczyła, Teresa Grabowska, Wojciech Waloszek, Michał Zawadzki
OF=: S EMS 06 :=
#2© 2006 KMG @ GUT
PIPS
KaSeA RDB
Data
Knowledge
Upper layers
KMS
Internet
KaSeA RDB
#3© 2006 KMG @ GUT
Motivations
• PIPS manages knowledge about: – ilnesses,– drugs,– alergies,– diets,– …
• Required data are gathered from many internet sources; the number of information is very large.
#4© 2006 KMG @ GUT
Knowledge Cartography
• Main assumptions:– Terminology is updated so rarely that it might be
considered constant in time.– A knowledge base is queried much more often
than updated (new individual assertions).– A knowledge base should be able to hold and
efficiently process information about large numbers of individuals.
#5© 2006 KMG @ GUT
Knowledge Cartography
• Developed to: – simplify reasoning on numerous objects
(individuals),– simplify storage of inferred results concerning
numerous individuals.
• Processes ontological information in accordance to Description Logics and Semantic Web standard.
#6© 2006 KMG @ GUT
Terminology – an example
• Terminology is described by a set of statements - axioms.
• Suppose, we want to describe the world of people and their pets:– There are no other creatures except People,
Dogs and Cats,– People, Dogs and Cats are disjoint,– Dogs and Cats are CreaturesHavingTails,– People and Cats can be
CreaturesTakingCareOfHygiene.
#7© 2006 KMG @ GUT
Map of concepts
There are no other creatures except People, Dogs and Cats
People Dogs Cats
#8© 2006 KMG @ GUT
Map of concepts
People, Dogs and Cats are disjoint
People Dogs People Cats Cats Dogs
#9© 2006 KMG @ GUT
Map of concepts
Dogs and Cats are CreaturesHavingTails
CreaturesHavingTails Dogs Cats
#10© 2006 KMG @ GUT
Map of concepts
People and Cats can be CreaturesTakingCareOfHygiene
CreaturesTakingCareOfHygiene PeopleCreaturesTakingCareOfHygiene Cats
#11© 2006 KMG @ GUT
Map of concepts
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Map of concepts – signatures
1
2
3
4 5
11000
00001
00111
01000
00010
11111
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Terminological queries
Must every person take care of hygenie?
11000
10011NO
Is a creature without a tail a person?
11000
11000
YES
Is a creature which have a tail and takes care of hygenie a cat?
00100
00110
YES
#14© 2006 KMG @ GUT
Individuals’ signatures
• Individuals’ signatures describe what we know and what we do not know about individuals
Source 1: Fred has a tail
00111
Is Fred a person?
00111
11000NO
Is Fred a dog?
00111
00001MAYBE
#15© 2006 KMG @ GUT
We know something more…Source 2: Fred takes care of hygenie
00111
01100
00100
Is Fred a dog?
00100
00001NO
Is Fred a cat?
00100
00110YES
,
#16© 2006 KMG @ GUT
Restrictions
• Role constructors in the form of R.C and R.C are treated as concepts
• Such constructors must be explicitly defined in ontology.
#17© 2006 KMG @ GUT
Deployment in PIPS
• Cartographic approach has been succesfully deployed in the first release of PIPS system,
• Allowed for achieving short (<1 s) response times for queries in knowledge bases with very large (>10000) number of individuals (sublinear scalability).
#18© 2006 KMG @ GUT
Future work
• Compression of signatures and hierarchical signatures,
• Introducing signatures not only for concepts but also for roles (relations) between individuals.
• Extending expresiveness of KaSeA in order to support complex queries (cardinality constraints, functional, symetric and transitive roles),
#19© 2006 KMG @ GUT
Thank you!
OF=: S EMS 06 :=