1. Character-Level Analysis of Semi-Structured Documents for Set Expansion Richard C. Wang and William W. Cohen Language Technologies Institute Carnegie Mellon University Pittsburgh, PA 15213 USA

2. Summary We illustrated… 1. the construction of character-based wrappers used in SEAL 2. a method to extend SEAL to learn binary relational concepts We showed that… 1. character-based wrappers perform better than HTML-based 2. binary SEAL has good performance

3. Background – SEAL Set Expander for Any Language  Wang & Cohen, ICDM 2007 An example of set expansion  Given an input query (seeds): { survivor, amazing race }  The output answer is: { american idol, big brother,... }

4. Features  Independent of human & markup language Support seeds in English, Chinese, Japanese,... Accept documents in HTML, XML, SGML, TeX, …  Does not require pre-annotated training data Utilize readily-available corpus: World Wide Web Research contributions  Automatically construct wrappers for extracting candidate items  Rank candidates using random walk

5. Fetcher: Download web pages containing all seeds Extractor: Learn and construct wrappers Ranker: Rank candidate items using Random Walk Canon Nikon Olympus Pentax Sony Kodak Minolta Panasonic Casio Leica Fuji Samsung … SEAL’s Architecture

6. Wrapper Learner Current WL only learns unary relation  e.g., x is a mayor  A unary wrapper consists of a pair of left (L) and right (R) context string  Extracts all strings between L, R Extended WL learns binary relation  e.g., x is the mayor of city y  A binary wrapper has an additional middle (M) context string  Extracts string pairs between L, M and M, R

7. Unary Relation Wrapper Construction

8. Real Unary Wrappers Given seeds: Ford, Nissan, Toyota Examples of wrappers and extractions:

9. Mock Unary Example Given seeds: Ford, Nissan, Toyota Example document written in an unknown mark-up language:

10. Context tries for mock example: Constructed unary wrappers:

11. Metric – Mean Average Precision Dataset – 36 datasets (Wang & Cohen, ICDM 2007) Evaluated on 5 types of wrappers  Type 1 is least strict – SEAL’s default  Type 5 is most strict – less strict than any HTML wrapper Result – stricter wrappers perform worse Unary SEAL Evaluation

12. Binary Wrapper Construction Keep track of all middle contexts: In the unary code, replace Intersect with:

13. Real Binary Wrappers

15. Binary SEAL Evaluation Relational Datasets  Surveyed more than a dozen  Randomly selected five: Bootstrap results ten times using iSEAL (an iterative version of SEAL)  Wang & Cohen, ICDM 2008

17. Unary SEAL Evaluation

18. Mock Binary Example Example document written in an unknown mark-up language: Given seeds: Ford, Nissan, Toyota