Exploring the Application Potential of Relational Web Tables
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The document discusses the application potential of relational web tables in enhancing knowledge bases through methods like table augmentation, data translation, and data fusion. It outlines the table augmentation process, which includes extraction, matching to existing knowledge bases, and fusion of values, along with specific applications and challenges encountered. The study highlights the significance of web table data for improving data quality and completeness but notes limitations in recall, particularly regarding less frequent entities.
Exploring the Application Potential of Relational Web Tables
- 1. Exploring the Application Potential of Relational Web Tables Prof. Dr. Christian Bizer Lernen, Wissen, Daten, Analysen (LWDA) Hasso Plattner Institute, Potsdam 13.9.2016
- 2. 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables 2 Hello Professor Christian Bizer University of Mannheim Research Topics • Web Technologies • Web Data Integration • Web Data Profiling
- 3. 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables 3 Data and Web Science Group @ University of Mannheim • 5 Professors • Heiner Stuckenschmidt • Rainer Gemulla • Christian Bizer • Simone Ponzetto • Heiko Paulheim • http://dws.informatik.uni-mannheim.de/ 1. Research methods for integrating and mining heterogeneous information from the Web 2. Empirically analyze the content and structure of the Web
- 4. 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables 4 Application Potential of Relational Web Tables Main applications so far 1. Table Augmentation 2. Data Translation
- 5. 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables 5 Table Augmentation Type 1: Create New Attributes No. Region Unemployment 1 Alsace 11 % 2 Lorraine 12 % 3 Guadeloupe 28 % 4 Centre 10 % 5 Martinique 25 % … … … GDP per Capita 45.914 € 51.233 € 19.810 € 59.502 € 21,527 € … + „GDP per Capita“ • Cafarella, Halevy, et al.: WebTables: Exploring the Power of Tables on the Web. VLDB 2008. • Yakout, et al.: InfoGather: Entity Augmentation and Attribute Discovery By Holistic Matching with Web Tables. SIGMOD 2012. • Lehmberg, et al.: The Mannheim Search Join Engine. Journal of Web Semantics 2015. Goal: Extend given table with additional attributes and fill attributes with values from the web tables.
- 6. 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables 6 Table Augmentation Type 2: Fill Missing Values • Interesting for cross-domain knowledge bases • Easier as more existing knowledge can be exploited Web Tables Corpus Country Capital Population Germany Berlin France 64,000,000 United Kingdom London 60,900,000 Canada USA Washington D.C. Mexico Mexico City 109,900,00 Country Capital Population Germany Berlin 82,000,000 France Paris 64,000,000 United Kingdom London 61,000,000 Canada Ottawa 33,000,000 USA Washington D.C. 304,000,000 Mexico Mexico City 110,000,00 • Dong, et al.: Knowledge Vault: A Web-Scale Approach to Probabilistic Knowledge Fusion. KDD 2014. • Ritze, et al: Profiling the Potential of Web Tables for Augmenting Knowledge Bases. WWW 2016.
- 7. 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables 7 The Table Augmentation Process 1. Extraction 2. Matching 3. Fusion Code Code
- 8. Outline 1. WDC Web Table Corpus 2. Matching the WDC Corpus to DBpedia 3. Fusing Web Table Data 4. Lessons Learned 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables 8
- 9. 1. Web Data Commons (WDC) Web Tables Corpus • Early research used tables from Google and Bing crawls • Cafarella/Halevy (2008): In corpus of 14B raw tables, 154M are “good” relations (1.1%). • Yakout, et al. (2012): 650M single-attribute tables • Problem: Crawls/tables not public, research not verifiable • Common Crawl enabled public research in this area • Series of 1.8-3.5 billion page public web crawls, since 2012 • Public Web Table Corpora • WDC Web Tables Corpus 2012: 147 million web tables • Dresden Web Tables Corpus 2014: 125 million web tables • WDC Web Tables Corpus 2015: 233 million web tables • http://webdatacommons.org/webtables 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables 9
- 10. Table Extraction & Classification 1. Common Crawl 2012 • 3,3b HTML pages • from 40m PLDs 2. HTML Table Extraction • 11b HTML tables 10 3. Layout vs. Relational Table Classification • 147m relational tables (1.3%) 4. Filtering by Size & Language • At least three columns & five rows • Only English language • 33m resulting tables Layout 98.7% Relational English Min. Size: 0.3% Relational Non- English Small: 1.0% 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables
- 11. Most Frequent Websites 11 Website # Tables Topic apple.com 50,910 Music baseball-reference.com 25,647 Sports latestf1news.com 17,726 Sports nascar.com 17,465 Sports amazon.com 16,551 Products wikipedia.org 13,993 Various inkjetsuperstore.com 12,282 Products flightmemory.com 8,044 Flights windshieldguy.com 7,305 Products citytowninfo.com 6,293 Cities blogspot.com 4,762 Various 7digital.com 4,462 Music 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables
- 12. 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables 12 Types of Web Tables 1. Relational Tables 2. Entity Tables Table Types in WDC 2015 Corpus #Type #Tables % of all tables Relational 90,266,223 0.90 Entity 139,687,207 1.40 Matrix 3,086,430 0.03 Sum 233,039,860 2.25 3. Matrix • Eberius, et al.: Building the Dresden Web Table Corpus: A Classification Approach. BDC 2015. • Qiu, et al.:, DEXTER: Large-Scale Discovery and Extraction of Product Specifications, VLDB 2015.
- 13. Assumptions of the Existing Extension Algorithms 1. Input is corpus of relational tables • One entity per row 2. Each table has a subject column • name of the entity • string, no number or other data type • used as pseudo-key • accuracy of automatic subject column detection: >90% Rank Film Studio Director Length 1. Star Wars –Episode 1 Lucasfilm George Lucas 121 min 2. Alien Brandwine Ridley Scott 117 min 3. Black Moon NEF Louis Malle 100 min 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables 13
- 14. 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables 14 • Manual annotation of 400 relational tables (1,814 columns) • Binary • Attribute depends only on subject column (key) • N-Ary • Attribute depends on subject key and other partial keys contained on the page around the table • e.g. type or date of competition in sports results Attribute Dependency on Subject Column Lehmberg, et al.: Web Table Column Categorisation and Profiling. WebDB 2016.
- 15. • T2K Matching Framework creates • Table-to-Class correspondences • Row-to-Instance correspondences • Column-to-Property correspondences • Size of DBpedia (2014) • 680 classes • 2700 properties • 4.5 million instances Year Game Company 2007 Portal Valve Corporation 2008 Fallout 3 Bethesda Game Studios 2009 Uncharted 2: Among Thieves Naughty Dog 2010 Red Dead Redemption Rockstar San Diego 2011 The Elder Scrolls V: Skyrim Bethesda Game Studios 2012 Journey Thatgamecompany 2013 The Last of Us Naughty Dog 2014 Middle-earth: Shadow of Mordor Monolith Productions 2015 The Witcher 3: Wild Hunt CD Projekt RED 2. Table Matching 15 DBpedia:Developer DBpedia:Portal DBpedia:VideoGame Ritze, et al.: Matching HTML Tables to DBpedia. WIMS 2015. 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables
- 16. T2K Table Matching Algorithm 16 Candidate Selection Class Decision Candidate Refinement Identity Resolution Schema Matching Candidate Class Distribution Add/Remove Candidates Tested on gold standard of 233 tables • 26,124 instance correspondences • 653 property correspondences Task Precision Recall F1 Instance .90 .76 .82 Property .77 .65 .70 Class .94 .94 .94 Iterate until results stabilize 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables Ritze, et al.: Matching HTML Tables to DBpedia. WIMS 2015.
- 17. • Approx. 1 million tables match DBpedia (~3%) • 13,726,582 instance correspondences • 562,445 property correspondences • 301,450 tables with property correspondences (ca. 32%) • = 8 million triples • Content variety • 274 different classes (40% of DBpedia) • 721 unique properties (26% of DBpedia) • 717,174 unique instances (15.6% of DBpedia) • Head vs. tail instances • 30% appear only once • 25% appear at least in 10 sources • 3% appear in more than 100 sources Table Matching Results 1709/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables
- 18. Table Matching – Detailed Results DBpedia Class Number of Tables/Values Number of Values per Data Type Tables T. w/ property Values Numeric Date String Reference Person 265 685 103 801 4 176 370 2 117 793 1 588 475 266 628 203 474 Athlete 243 322 95 916 3 861 641 2 084 017 1 435 775 163 771 178 078 Artist 9 981 2 356 18 886 3 11 527 3 499 3 857 Politician 3 701 1 388 18 505 10 7 725 3 393 7 377 Office Holder 2 178 1 435 131 633 30 66 762 59 332 5 509 Organisation 194 317 36 402 573 633 99 714 187 370 100 710 185 839 Company 97 891 6 943 203 899 58 621 83 001 34 665 27 612 Sports Team 50 043 2 722 31 866 2 206 22 368 43 7 249 Educational Inst. 25 737 14 415 238 365 38 056 64 578 13 334 122 397 Broadcaster 14 515 11 315 93 042 564 13 095 52 186 27 197 Work 269 570 127 677 2 284 916 109 265 1 354 923 33 091 787 637 Musical Work 138 676 80 880 1 131 167 64 545 396 940 7 610 662 072 Film 43 163 9 725 256 425 10 844 198 913 14 382 32 286 Software 39 382 23 829 486 868 418 414 092 9 194 63 164 Place 133 141 24 341 859 995 413 375 273 510 84 111 88 999 Populated Place 119 361 21 486 787 854 405 406 257 780 57 064 67 604 Country 36 009 6 556 208 886 93 107 66 492 31 793 17 494 Settlement 17 388 2 672 17 585 4 492 6 662 2 444 3 987 Region 12 109 427 5 625 3 097 897 292 1 339 Architect. Struct. 10 136 1 815 46 067 3 976 7 387 23 110 11 594 Natural Place 1 704 254 2 568 866 696 340 666 Species 14 247 4 893 83 359 - 7 902 38 682 36 775 Σ 949 970 301 450 8 037 562 2 751 105 3 437 420 536 526 1 312 511 1809/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables
- 19. 3. Data Fusion • Next Step: Estimate the quality of the values that can be added to the knowledge base • Quality depends on data fusion strategy • Recent research in this area • Knowledge-based Trust as fusion strategy (KBT) • Local Closed World Assumption for evaluation (LCWA) 19 Country City Germany Berlin France Paris United Kingdom London Canada Ottawa USA Washington D.C. Mexico Ecatepec Web Table ? ? Country Capital Germany Berlin France United Kingdom London Canada USA Washington D.C. Mexico Mexico City Knowledge Base 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables Dong, et al.: Knowledge Vault: A Web-Scale Approach to Probabilistic Knowledge Fusion. KDD 2014.
- 20. Data Fusion – Approach 1. Calculate different trust scores 1. Baseline: All sources get same score, e.g. 1.0 2. Knowledge-based Trust: Overlap of values in table and KB 3. PageRank: PageRank of the web site containing the table 2. Remove values with score below threshold 3. Determine a final value using weighted voting / median 20 Source Value Score A 8,000,000 0.3 B 81,459,000 1.0 C 81,900,000 0.8 Germany/Population 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables
- 21. Data Fusion – Evaluation 21 Strategy Precision Recall F1 Baseline .369 .823 .509 Knowledge-based Trust .639 .785 .705 PageRank .365 .814 .504 • Evaluation Results • Group Sizes • For 58% of all groups we have at least two alternative sources • Frequent (Head entities): likely already exist in the KB • Infrequent (Tail entities): likely new, but hard to fuse 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables
- 22. 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables 22 Data Fusion – Detailed Results DBpedia Class Existing Values New Values Precision Recall F1 Person 117 522 15 050 0.639 0.723 0.678 Athlete 84 562 9 067 0.646 0.679 0.662 Artist 2 019 427 0.711 0.830 0.766 Office Holder 3 465 510 0.698 0.849 0.766 Politician 3 124 1 167 0.533 0.765 0.628 Organisation 20 522 7 903 0.645 0.691 0.667 Company 6 376 2 547 0.700 0.834 0.761 Sports Team 790 132 0.671 0.892 0.766 Educational Inst. 8 844 3 132 0.638 0.714 0.674 Broadcaster 4 004 1 924 0.557 0.459 0.503 Work 189 131 27 867 0.614 0.828 0.705 Musical Work 118 511 8 427 0.599 0.830 0.695 Film 29 903 12 143 0.573 0.803 0.669 Software 17 554 2 766 0.591 0.760 0.665 Place 32 855 9 871 0.767 0.858 0.810 Populated Place 16 604 6 704 0.711 0.779 0.743 Country 2 084 433 0.738 0.690 0.713 Settlement 540 224 0.583 0.669 0.623 Region 362 70 0.587 0.784 0.671 Architectural Struct. 10 441 1 775 0.834 0.940 0.884 Natural Place 743 64 0.843 0.940 0.889 Species 9 016 1 429 0.783 0.892 0.834
- 23. 4. Lessons Learned • Web Table data is useful for KB completion, but • Small number of new values in comparison to overall input • Challenge: Improve matching recall, especially for long tail entities • Ongoing work: • Exploit table context to improve matching • Further improve value normalization (surface forms of names, units of measurement) to improve matching • Knowledge-based trust outperforms other fusion strategies • F1 = 0.7 is below the quality required for automating the task • Shortcoming: Time dimension not taken into account • Ongoing work: Exploit timestamps in webpages and tables 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables 23 Oulabi, et al.: Fusing Time-Dependent Web Table Data. WebDB 2016.
- 24. Exploiting other Types of Web Data 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables 24 Lehmberg, et al.: The Mannheim Search Join Engine. Journal of Web Semantics 2015. Public Data Corpora • Microdata: Web Data Commons Corpus. http://webdatacommons.org/structureddata/ • HTML Tables: Web Data Commons Table Corpus. http://webdatacommons.org/webtables/ • Wiki Tables: Northwestern University Corpus. http://downey-n1.cs.northwestern.edu/public/ • Linked Data: Billion Triples Challenge 2014: http://km.aifb.kit.edu/projects/btc-2014/ schema.org Microdata Linked Data Entity Tables Data Portals
- 25. Thank you! http://webdatacommons.org/webtables 09/13/2016 Bizer: Exploring the Application Potential of Relational Web Tables 25
Editor's Notes
- #14: Subject Attribute Detection (Ventis, et al.: Recovering Semantics of Tables on the Web. VLDB 2011) Simple heuristic approach (Accuracy: 83%) take first column from the left of Web tables that is not a number or a date SVM Classifier (Accuracy: 94%) fraction of cells with unique content, variance in the number of tokens in each cell, column index from the left, …