1. Infomaster: An information Integration Tool O. M. Duschka and M. R. Genesereth Presentation by Cui Tao

2. Introduction  Huge amount of information online: – Distribution: Not every query can be answered by the data in a single database Fragmentation: horizontal, vertical – Heterogeneity Notational heterogeneity: –Different access language and protocol: Parsing HTML, SQL, OQL, Z39.50 Conceptual heterogeneity: –Semantic mismatches – Instability

3. Introduction  Intelligent agents – Search and find desired information – Convert formats – Translate different context – Etc… – Not feasible yet – Considerable research in ontologies and natural language understanding is required

4. Introduction  Infomaster: an information integration tool – Provide integrated access – Manage evolving information sources – Add new information sources – Remove outdated information sources

5. Architecture

6. Tested Application Areas  Newspaper classifieds – Provide a uniform search interface – Gather corresponding classifieds from all relevant newspapers  Product catalogs – Provide terminology translation  Campus databases

7. Abstraction Hierarchy

8. Descriptions of Relationships  Interface relation & Site relation: in the terms of Base relation  Interface relation v.s. Base relation: Interface Base

9. Descriptions of Relationships  Site relation v.s. Base relation: Base Site

10. Descriptions of Relationships  Site relation v.s. Base relation: Base Site

11. Query Processing Example: BMWs built in 1996 that are for sale for a Price below their average market value.

12. Reduction: Interface relations  Base relations  Simple: User’s query --- Interface relation --- Base relation  Example rewritten query:

13. Abduction Base relations  Site relations  Site relations are expressed in terms of base relations, but not vice versa  Query rewritten problem: answer queries using views  Abduction: use a standard model elimination theorem prover

14. Abduction Base relations  Site relations  : The set of all descriptions of the site relations  : A set of site relations  : The rewritten user query after the reduction step

15. Abduction Base relations  Site relations  The example query plans:

16. Optimization Assume: All ads in sjmn are in sfc

17. Conclusions  The first integration system: – Arbitrary positive relational algebra user queries – DB description  Efficient optimization by use: – Integrity constraints – Local completeness information  Flexible Use of query planning: – Expressive description language – Constraint – Background theories

18. Related Works  Information Manifold project and SIMS project: – Explore the use of descriptions logics for describing information sources  Occam project – Use general AI planning techniques to generate information gathering plans  TSIMMIS project – Use pattern matching techniques to match user queries and predefined queries.