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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 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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Problem Detecting The Table of Interest ?
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Problem 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} Different schemas
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Problem Attribute is Value
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Problem Attribute-Value is Value ??
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Problem Value is not Value
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Problem Factored Values
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Problem Split Values
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Problem Merged Values
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Problem Information Behind Links Single-Column Table (formatted as list) Table extending over several pages
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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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Solution Detect The Table of Interest ‘Real’ table test Same number of values Table size Attribute test Density measure test # of ontology extracted values total # of values in the table
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Solution Remove Factoring 2001 2000 1999
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Solution Replace Boolean Values
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Solution Form Attribute-Value Pairs,,,,,,,
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Solution Adjust Attribute-Value Pairs,,,,,,,
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Solution Add Information Hidden Behind Links Unstructured and semi-structured: concatenate,,,,,,,,, Single attribute value pairs: Pair them together List: Mark the beginning and the end < >
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Solution Inferred Mapping Creation {Car, Year, Make, Model, Mileage, Price, PhoneNr}, {Car, Feature}
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Solution Inferred Mapping Creation {Car, Year, Make, Model, Mileage, Price, PhoneNr}, {Car, Feature} Each row is a car.
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Solution Inferred Mapping Creation {Car, Year, Make, Model, Mileage, Price, PhoneNr}, {Car, Feature}
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Solution Inferred Mapping Creation {Car, Year, Make, Model, Mileage, Price, PhoneNr}, {Car, Feature}
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Solution Inferred Mapping Creation {Car, Year, Make, Model, Mileage, Price, PhoneNr}, {Car, Feature}
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Solution Inferred Mapping Creation {Car, Year, Make, Model, Mileage, Price, PhoneNr}, {Car, Feature}
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Solution Inferred Mapping Creation {Car, Year, Make, Model, Mileage, Price, PhoneNr}, {Car, Feature}
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Experimental Results Car Advertisement Application domain 10 “training” tables 100% of the 57 mappings (no false mappings) 94.6% precision of the values in linked pages (5.4% false declarations) 50 test tables 94.7% of the 300 mappings (no false mappings) On the bases of sampling 3,000 values in linked pages, we obtained 97% recall and 86% precision
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Other Applications Cell Phone Plan Application domain Soccer Player Application domain
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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
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