1. Learning Patterns on the World Wide Web Andrew Hogue Advisor: David Karger October 17, 2003

2. Agenda What is a pattern? How do we make one? How do we use it? Why do you want one? Demo

3. What is a pattern? Objects in the world have certain semantic properties A pattern is a way of recognizing the semantic properties of an object we’ve seen before A pattern is a structure with semantic slots to be filled in

4. Example – Books Define an object’s semantics (ontology): Class: Book Property: Author Property: Title Property: Price Property: Publisher Property: ISBN...

5. Class: Book Property: Author Property: Title Property: Price Property: Publisher Property: ISBN... Example - Books ? ?

6. Class: Book Property: Author Property: Title Property: Price Property: Publisher Property: ISBN...

7. Example - Books Class: Book Property: Author Property: Title Property: Price Property: Publisher Property: ISBN...

8. Creating a Pattern Choose positive examples

9. Creating a Pattern

11. Choose positive examples Find best mapping between examples

12. Creating a Pattern

13. Choose positive examples Find best mapping between examples Merge mapped elements and assign semantic labels

14. Creating a Pattern

18. Choose positive examples Find best mapping between examples Merge mapped elements and assign semantic labels Eliminate unmapped elements

19. Creating a Pattern

21. Matching Patterns Given a pattern with slots and a page to search Look for items on page with same structure Map pattern slots to page text

22. Matching Patterns

24. Applications Extract search engine results Extract and email news headlines Watch sites for updates Reformat sites for easier reading Monitor bank account balances

25. Demo

26. More Information http://haystack.lcs.mit.edu ahogue@mit.edu