A Semi-automatic Ontology Acquisition Method for the Semantic Web Man Li, Xiaoyong Du, Shan Wang Renmin University of China, Beijing WAIM May 2012 SNU IDB Lab. Hye Chan, Bae

Outline  Introduction  SOAM  Case Study  Conclusion  Discussion 2

Introduction  The Semantic Web aims to add – Semantics – Better structure to the information 3

Introduction  Success of Semantic Web depends on – The proliferation of ontologies – Pay more attention to the construction of ontologies 4 How do I construct the ontology?

Introduction  Manual development of ontologies still remains a tedious and cumbersome task 5

Introduction  A large amount of data about various domains are organized and stored in relational database 6

Introduction  SOAM – Semi-automatic Ontology Acquisition Method – Based on data in relational database – Balance the cooperation between user contributions and machine learning  Acquire ontology directly by using a group of rules  Refine ontology according to lexical knowledge repositories (semi-automatically) 7

SOAM overview Step4: Acquire ontological instances based on refined ontological structure Step3: Refine the obtained ontological structure Step2: Acquire ontological structure according to the database schema information Step1: Capture the information about relational database schema 8

SOAM overview 9

Acquiring Ontological Structure  Prior assumption – Relational schema is at least in 3NF  We have 11 rules for acquiring ontological structure!! 10

Acquiring Ontological Structure Rule 1 R1 A1 A2 A3 11 R2 A1 A4 R3 A1 A5 A6 RiRi A1 A2 A3 A4 A5 A6 Class C i Equivalence

Acquiring Ontological Structure Rule 2 RiRi A1 A2 A3 12 RiRi A1 A2 A3 A4 RjRj A3 A5 A6 Class C i

Acquiring Ontological Structure Rule 2 13 RiRi A1 A2 R2 A2 A5 Class C i R1 A1 A3 A4

Acquiring Ontological Structure Rule 3 14 RiRi A1 A2 A3 RjRj A4 A5 Class C i Class C j A3 Inclusion dependency

Acquiring Ontological Structure Rule 4 15 RiRi A1 A2 A3 A4 RjRj A2 A3 A5 Class C i Class C j is-part-of has-part-of

Acquiring Ontological Structure Rule 5 16 RkRk A1 A2 RjRj A5 RiRi A1 A3 A4 Class C i Class C j

Acquiring Ontological Structure Rule 6 17 RlRl A1 A2 A3 RjRj A2 A6 RiRi A1 A4 A5 Class C i Class C j RkRk A3 A7 Class C k

Acquiring Ontological Structure Rule 7 18 RiRi A1 A2 A3 Class C i String Number Datatype property A1 A2 A3

Acquiring Ontological Structure Rule 8 19 RiRi A1 A2 A3 RjRj A1 A4 A5 Inclusion dependency Class C i subclass-of

Acquiring Ontological Structure Rule 1 (ref.) 20 RiRi A1 A2 A3 RjRj A1 A4 A5 Equivalence Class C j RiRi A1 A2 A3 A4 A5

Acquiring Ontological Structure Rule 9, 10, RiRi A1 A2 A3 Class C i A1 minCardinality=1 maxCardinality=1 NOT NULL : minCardinality = 1 UNIQUE : maxCardinality = 1

Refining Ontological Structures  The obtained ontological structure is coarse  Refining obtained ontology according to machine-readable – dictionaries – thesauri 22

Refinement algorithm  The basic idea 1.A user wants to refine a concept in the ontology 2.The algorithm can help him find some similar lexical entries 3.The user can refine the concept according to the information 23 Concepts k most similar lexical entries

Similarity measures  Lexical similarity – Edit distance method is used (LSim)  Similarity in conceptual level – Considers the similarity about  Super-concepts (SupSim)  Sub-concepts (SubSim) 24

Case Study 25

Conclusion  Gives a semi-automatic ontology acquisition method – Based on data in relational database  Future work – Apply our approach in other domains – Do some researched on acquiring ontology from other resources  Natural language text  XML  And so on 26

Discussion  Strong point – More practical rules for real data in relational database? – Refinement using lexical repositories  Weak point – No example  Hard to understand the rules fully – Need to understand more about ontology languages  OWL 27

Thank you!!! 28