Schema Matching and Data Extraction over HTML Tables

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Schema Matching and Data Extraction over HTML
Tables

• Cui Tao
• Data Extraction Research Group
• Department of Computer Science
• Brigham Young University

supported by NSF
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Introduction

• Many tables on the Web
• Ontology-based extraction
• Works well for unstructured or semi-structured
  data
• What about structured data tables?
• How to integrate data stored in different tables?
• Detect the table of interest
• Form attribute-value pairs (adjust if necessary)
• Do extraction
• Infer mappings from extraction patterns

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ProblemDetecting The Table of Interest
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Problem
Different schemas

• Different source table schemas
• Run , Yr, Make, Model, Tran, Color, Dr
• Make, Model, Year, Colour, Price, Auto, Air
  Cond., AM/FM, CD
• Vehicle, Distance, Price, Mileage
• Year, Make, Model, Trim, Invoice/Retail, Engine,
  Fuel Economy
• Target database schema
• Car, Year, Make, Model, Mileage, Price,
  PhoneNr,
• Car,
  Feature

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ProblemAttribute is Value
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Problem Attribute-Value is Value
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ProblemValue is not Value
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ProblemFactored Values
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ProblemSplit Values
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ProblemMerged Values
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ProblemInformation Behind Links
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Solution

• Detect the table of interest
• Form attribute-value pairs (adjust if necessary)
• Do extraction
• Infer mappings from extraction patterns

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SolutionDetect The Table of Interest

• Top-level tables
• Table size at least 3 rows and columns
• Grid layout same of values
• Attributes
• Value density
• of ontology extracted values
• total of values in the table

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SolutionDetect The Table of Interest

• Linked-page tables
• Table size at least 2 rows and columns
• Attributes
• Attribute-value-pair pattern
• Page-spanning tables

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Solution Remove Factoring
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SolutionReplace Boolean Values
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SolutionForm Attribute-Value Pairs
ltMake, Hondagt, ltModel, Civic EXgt, ltYear, 1995gt,
ltColour, Whitegt, ltPrice, 6300gt, ltAuto,
Autogt, ltAir Cond., Air Cond.gt, ltAM/FM, AM/FMgt
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SolutionAdjust Attribute-Value Pairs
ltMake, Hondagt, ltModel, Civic EXgt, ltYear, 1995gt,
ltColour, Whitegt, ltPrice, 6300gt, ltAuto,
Autogt, ltAir Cond., Air Cond.gt, ltAM/FM, AM/FMgt
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SolutionAdd Information Hidden Behind Links
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SolutionInferred Mapping Creation
Car, Year, Make, Model, Mileage, Price,
PhoneNr, Car, Feature
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SolutionInferred Mapping Creation
Car, Year, Make, Model, Mileage, Price,
PhoneNr, Car, Feature
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SolutionInferred Mapping Creation
Car, Year, Make, Model, Mileage, Price,
PhoneNr, Car, Feature
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SolutionInferred Mapping Creation
Car, Year, Make, Model, Mileage, Price,
PhoneNr, Car, Feature
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SolutionInferred Mapping Creation
Car, Year, Make, Model, Mileage, Price,
PhoneNr, Car, Feature
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SolutionInferred Mapping Creation
Car, Year, Make, Model, Mileage, Price,
PhoneNr, Car, Feature
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SolutionInferred Mapping Creation
Car, Year, Make, Model, Mileage, Price,
PhoneNr, Car, Feature
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SolutionInferred Mapping Creation
Car, Year, Make, Model, Mileage, Price,
PhoneNr, Car, Feature
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Experimental Results - Table Location

• Car advertisement application domain

Precision86 Recall 92
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Experimental Results - Mapping

• Car advertisement application domain
• 46 recognized tables in the testing set
• Total 319 mappings
• Precision 95.8 Recall 92.8
• Top-level tables 77 of the 296 correct mappings
• Linked tables 19.6
• Both 3.4

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Experimental Results - Table Location

• Cell-phone sales application domain

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Experimental Results - Mapping

• Cell-phone sales application domain
• 11 recognized tables in the testing Set
• Total 97 mappings
• Precision 90.1 Recall 85.4
• Top-level tables 85.4 of the 88 correct
  mappings
• Linked tables 50.5
• Both 35.9

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Contribution

• Provides an approach to extract information
  automatically from HTML tables
• Suggests a different way to solve the problem of
  schema matching