Infomaster: An Infomaster: An information Integration information Integration

ToolTool

O. M. Duschka and M. R. GeneserethPresentation by Cui Tao

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

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

Introduction

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integration tool– Provide integrated access– Manage evolving information sources– Add new information sources– Remove outdated information sources

Architecture

Tested Application Areas

Newspaper classifieds– Provide a uniform search interface– Gather corresponding classifieds from all

relevant newspapers

Product catalogs– Provide terminology translation

Campus databases

Abstraction Hierarchy

Descriptions of Relationships

Interface relation & Site relation: in the terms of Base relation

Interface relation v.s. Base relation:Interface

Base

Descriptions of Relationships

Site relation v.s. Base relation:

Base

Base

Site

Descriptions of Relationships

Site relation v.s. Base relation:

Base

Base

Site

Query Processing

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

Reduction: Interface relations Base relations

Simple:

User’s query --- Interface relation --- Base relation

Example rewritten query:

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

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

Abduction Base relations Site relations

The example query plans:

Optimization

Assume: All ads in sjmn are in sfc

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

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.