Semantic Search Engines

Semantic Search Engines based on Data Integration Systems Chapter 13

Agenda ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Motivation ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Ingredients for Semantic Search Engines (1) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Ingredients for Semantic Search Engines (2) ,[object Object],[object Object],[object Object],[object Object],[object Object]

MOMIS ,[object Object],[object Object],[object Object],[object Object],[object Object]

SEWASIE ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

WISDOM ,[object Object],[object Object],[object Object],[object Object],[object Object]

The SEWASIE architecture Query Results Brokering Agent (BA) BA Ontology Monitoring Agent (MA ) Query Tool Interface OLAP Tool SINode Structured Databases RDBs Wrapper Query Metadata Repository Semi - Databases Wrapper <XML> <DATA>... </DATA> Wrapper Unstructured Text documents <HTML> ... Structured Databases RDBs Wrapper Query Manager Ontology Databases Wrapper <XML> <DATA>... Wrapper <HTML> ... Ontology Builder Structured Query Agent Query Agent Query Agent SINode SINode SEWASIE Interconnection infrastructure BA BA BA BA Brokering Agent (BA)

SEWASIE - Goal ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The two different levels of mapping

The two-level data integration system ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Integration System: Semantics ,[object Object],[object Object],[object Object],[object Object]

Building the SEWASIE system ontology (GVV) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Overview of the GVV-generation process AUTOMATIC/ MANUAL ANNOTATION SEMI-AUTOMATIC ANNOTATION INFERRED RELATIONSHIPS LEXICON DERIVED RELATIONSHIPS SCHEMA DERIVED RELATIONSHIPS Common Thesaurus COMMON THESAURUS GENERATION USER SUPPLIED RELATIONSHIPS ODLI3 LOCAL SCHEMA N WRAPPING ODLI3 LOCAL SCHEMA 1 … GVV GENERATION MAPPING TABLES GLOBAL SCHEMA (ODLI3) clusters generation Structured source RDB <XML> <DATA> Semi-Structured Source SYNSET 1 SYNSET # SYNSET 2 WNEditor

Building the Mappings: q N definition ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Building the Mappings: an example from T_SN1 full join T_SN2 Join Attribute on (T_SN1.COMPANY_ID = T_SN2.COMPANY_ID) Join Conditions Full Disjunction Select COMPANY_ID, precedence(T_SN1.ADDRESS, T_SN2.ADRESS) as Address, T_SN2.SUBCONTRACTOR, … Resolution Functions Precedence(SN1,SN2) ... ADDRESS ADDRESS ADDRESS REGION REGION REGION CAPITAL_STOCK CAPITAL_STOCK SUBCONTRATOR SUBCONTRATOR COMPANY_ID, COUNTRY_ID COMPANY_ID COMPANY_ID SN2.company SN1.company

Data Conversion Functions ,[object Object],[object Object],[object Object],[object Object]

Join Conditions ,[object Object],[object Object],[object Object],[object Object]

Resolution Functions ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Full Disjunction ,[object Object],[object Object],[object Object],[object Object],[object Object]

Full Disjunction Computation (1/2) ,[object Object],[object Object],[object Object],Example with n = 3 : L1 L2 L3 JC(L1,L3) JC(L1,L2) JC(L2,L3)

Full Disjunction Computation (2/2) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Querying the SEWASIE system ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Query Reformulation ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Query unfolding ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Query unfolding : Atomic constraint mapping ,[object Object],[object Object],[object Object],[object Object],[object Object]

Query unfolding : Select-list computation ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Query unfolding : FDExpr and Resolution Functions ,[object Object],[object Object],[object Object],[object Object],[object Object]

SEWASIE Query Management: functional architecture SINodeAgent1 Query UNFOLDER ExpAtoms EXPANDER PLAY MAKER BROKERING AGENT BA Ontology QUERY AGENT END USER QUERY TOOL SEWASIE_DB Expanded Query: EXPQuery ExpAtoms Unfolding: FDExpr , FDAtoms , ResFunctions Query Result EXECUTION + FUSION + FINAL RESULT FDAtoms FDAtoms Answers to FDAtoms Answers to FDAtoms Map Keeper BBA-GVV SINodeAgent2 mapping

SEWASIE Query Management: EXPANDER UNFOLDER Librarian SINodeAgent2 SINodeAgent1 Query ExpAtoms EXPANDER PLAY MAKER BROKERING AGENT BA Ontology QUERY AGENT SEWASIE_DB scq1: SELECT CATEGORY_ID FROM Mould_Making scq2: SELECT NAME,COMPANY_ID,CAPITAL_STOCK, REGION,SUBCONTRACTOR,ADDRESS FROM company WHERE CAPITAL_STOCK > 50 AND AND REGION LIKE 'VENETO' AND SUBCONTRACTOR LIKE ’yes’ scq3: ... Expanded Query: EXPQuery EXPQuery: SELECT r2.NAME,r2.ADDRESS,r2.NATION FROM scq1 r1,scq2 r2,scq3 r3 WHERE r1.CATEGORY_ID=r3.CATEGORY_ID AND r2.COMPANY_ID=r3.COMPANY_ID UNION SELECT r2.NAME,r2.ADDRESS,r2.NATION FROM scq4 r1,scq2 r2,scq3 r3 WHERE … UNION … END USER QUERY TOOL Query

SEWASIE Query Management: UNFOLDER UNFOLDER SewasieRepository Query ExpAtoms Expanded Query: EXPQuery ExpAtoms Unfolding: FDQuery , FDAtoms , ResFunctions EXPANDER PLAY MAKER BROKERING AGENT BA Ontology QUERY AGENT Query ,[object Object],[object Object],[object Object],[object Object],Full Disjunction: FDQuery: SELECT * FROM FDAtom1 OUTER JOIN FDAtom1 ON (FDAtom1.COMPANY_ID = FDAtom2.COMPANY_ID) scq2: SELECT NAME,COMPANY_ID,CAPITAL_STOCK, REGION,SUBCONTRACTOR,ADDRESS FROM company WHERE CAPITAL_STOCK > 50 AND AND REGION LIKE 'VENETO' AND SUBCONTRACTOR LIKE ’yes’ Resolution Function: precedence ( ${SI-NMAgent2.company.ADDRESS}, ${SI-NMAgent1.company.ADDRESS}) END USER QUERY TOOL

UNFOLDER Librarian SINodeAgent2 SINodeAgent1 Query ExpAtoms Expanded Query: EXPQuery ExpAtoms Unfolding: FDQuery , FDAtoms , ResFunctions EXPANDER PLAY MAKER BROKERING AGENT BA Ontology QUERY AGENT Query SEWASIE_DB ,[object Object],[object Object],END USER QUERY TOOL

The Query Agent : EXECUTION UNFOLDER Librarian SINodeAgent2 SINodeAgent1 EXPANDER PLAY MAKER BROKERING AGENT BA Ontology QUERY AGENT ,[object Object],[object Object],[object Object],[object Object],EXECUTION SEWASIE_DB FDAtoms Answer to FDAtoms FDAtoms Answer to FDAtoms END USER QUERY TOOL

The Query Agent : FUSION UNFOLDER Librarian SINodeAgent2 SINodeAgent1 EXPANDER PLAY MAKER BROKERING AGENT BA Ontology QUERY AGENT EXECUTION FUSION ,[object Object],[object Object],[object Object],[object Object],[object Object],SEWASIE_DB END USER QUERY TOOL

The Query Agent : FINAL RESULT UNFOLDER Librarian SINodeAgent2 SINodeAgent1 SEWASIE_DB EXPANDER PLAY MAKER BROKERING AGENT BA Ontology QUERY AGENT EXECUTION FUSION FINAL RESULT ,[object Object],[object Object],[object Object],[object Object],END USER QUERY TOOL

Querying SEWASIE: Interface (available at www.sewasie.org)

WISDOM: Semantic peer and Wrappers ,[object Object],[object Object],Global Virtual View Data source schema Wrapper Web source

WISDOM: Semantic peer network

Peer-to-Peer Mapping and Query Processing ,[object Object],[object Object],[object Object],We associate every peer-to-peer mapping with a content summary. Given a pair of semantic peers for which it exists a peer-to-peer mapping, the content summary associated with such a mapping provides quantitative information about the extension of the concepts in the source ontology that can be found through the mapping in the target semantic peer.

Wrapping Large Web Sites ,[object Object],[object Object],[object Object],[object Object]

Wrapping Large Web Sites Web site Site model Given a large web site composed by thousands of interconnected page, we aim at producing model , that describes at the intensional level the structure of the site.

Query Processing : formulation ,[object Object],[object Object],[object Object]

Query rewriting and peers selection ,[object Object],[object Object],[object Object],[object Object],At Web scale [giving a complete answer to every query] is unfeasible and query execution must move to a probabilistic world of evidence accumulation and away from exact answers.

Query Processing : execution ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Conclusion ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Future Work ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Semantic Search Engines

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Semantic Search Engines