1. Intelligent Web Topics Search Using Early Detection and Data Analysis by Yixin Yang Presented by Yixin Yang (Advisor Dr. C.C. Lee) Presented by Yixin Yang (Advisor Dr. C.C. Lee) July 30, 2003

2. Outline 1. Introduction and Background 2. Related Work 3. Our Approach 4. System Architecture 5. Crawl Algorithms and Implementation 6. Experimental result 7. Conclusions and Future Work

3. Introduction and Background

4. General-purpose search engine Problem with General-purpose search engine : These search engines lack the capabilities of finding the relevant web sites for a giving specific topic General-purpose search engine: designed to crawl and index the web, get pages as many as possible

5. Topic-specific Search Engine Topic-specific search engine: focuses on one or a limited number of topics, get topic-related pages as fast as possible without deviating to unrelated pages. To help the topic-specific search engines to crawl the related hyperlinks, the relevant topics should provide to topic-specific search engines in advance.

6. Topic-specific Search Engine Sample Internet directories like Yahoo!, or topic- specific search engine like MathSearch offer higher quality, they construct a hierarchy for topic, but they require intensive human efforts (hierarchy will be maintained by humans to update ) Google rates sites based on how frequently someone links to a page -- the more links, the more relevant. Essentially, it harnesses human judgment.

7. Topic-specific Search Engine Sample (cont.) Focused Crawler utilizes both web link structure information and content similarity (based on document classification), but this system unnecessarily visits too many irrelevant pages.

8. Metadata in Web Documents Metadata of a page x, is the description about the page, x, furnished by other page y, that hyperlink to x. Analogy: Citation in a research paper x y1 y2 y3

9. Metadata in HTML 1.Anchor ( ) tags 2.Image ( ) tags 3.Map and Area tags 4.Frame tags Each of tags have attributes associated with them. Anchor and Area: name, title, alt, href … Image: alt, src, dynsrc, lowsrc … Anchor text ( text ) Four kinds of Hyperlinks in HTML document

10. Metadata Experiment by J. Yi and N. Sundaresan Studied a sample set of 20, 000 HTML pages, and 206,000 hyperlink references Showed anchor text are most frequently used and reliable Metadata TypeHyperlinksPages ALT tag 1890 (0.9%)281 (1.5%) Anchor Text 147745 (72%)14320 (76%) HREF 176412 (85%)16313 (87%) NAME 5487 (27%)779 (4.1%) ONMOUSEOVER 9383 (4.5%)1523 (8.1%) Surrounding Text 49183 (24%)8424 (45%) Title 885 (0.4%)249 (1.3%)

11. Target topics, Candidate topics and Relevant topics Target Topics: the topics that may consist of many sub-topics. Relevant Topics: the topics that related to a target topic. Candidate Topics: the topics that potentially relevant to a target topic.

12. Related Work

13. Recent Research in Topic-specific Search Engine :Topic Expansion Algorithm Presented by Jeonghee Yi and Neel Sundaresan Discovers relevant topics of a given topic Does not need to visit unnecessary web pages and does not need intensive human effort.

14. Recent Research in Topic-specific Search Engine :Topic Expansion Algorithm ( cont.) Four steps in Topic Expansion Algorithm: 1. Collects large number of Web pages 2. Extracts words from the text that is contained inside HTML document tags 3. Selects some words that are potentially relevant to the target topic. 4. Uses a formula and a relationship-based architecture for finding the relation between words to refine and return the relevant topics.

15. What is confidence? A good way to explain confidence is using association rule. An association rule is an expression X =>Y, where X and are sets of items. The intuitive meaning of such a rule is that transaction in database which contain the items in X also contain the items in Y.

16. Formula By J. Yi and N. Sundaresan

17. Recent Research in Topic-specific Search Engine :Topic Expansion Algorithm ( cont.) Topic Expansion Algorithm does not need to visit unnecessary web pages and does not need intensive human effort. But it still needs : much human involvement to update the architecture many web pages of Web sites crawling

18. Our Research

19. Our Approach Uses early detection and data analysis techniques for detecting and analyzing candidate topics Add Stop Word Filter, Candidate topic Selector, Candidate topic filter to the typical web crawler Simplify the formula used by J. Yi and N. Sundaresan

20. Formula we used:

21. System Architecture

23. Components in Our System Web Crawler Page Parser Stop Word Filter Candidate Topic Selector Candidate Topic Filter Relevant Term Database

24. Crawl Algorithms and Implementation

25. Crawl Algorithms: just like the typical Web Crawler Starts with a (set of) predefined web URLs and downloads them Breath-first-search Uses Recursion

26. This system: add something inside typical web crawler

27. Implementation : Language and Technology Java Programming Language Java HTTP Request Java AWT and Swing Java Database Connectivity (JDBC)

28. Databases Used for this system:

29. 10 components implemented for this system: WebCrawler HttpPage HTMLparser CandidateTopicFilter CandidateTopicSelector, StopWordFilter, StopWordsTable, Tokens.DoStat, DBAccess

30. Important Components HTMLparser Parses HTML pages and Extracts the Meta data. Uses javax.swing.test.html parser package to parse the HTML page. Get the text inside tags StopWordsTable When start the whole application, read the stop words from Database “stop_words” table and put every word into a Hash table.

31. Important Components (cont.) StopWordFilter Reads the words extracted from Metadata one by one, if a token can also be found in “stop_words” hush table, remove this word.

32. Important Components (cont.) CandidateTopicSelector Reads one string (tokens) processed by Stop word filter The attribute “total_num” for every word (except target topic) increase one if find target topic inside this string, the attribute “co_occur_num” for every word inside this string (except target topic) also increase one

33. Important Components (cont.) CandidateTopicFilter Check every words inside the “candidate_topics” table, and calculate every words by this formula: if words meet the requirement,put these words to “relevant_terms” table.

34. Formula we used:

35. Experimental result

36. Run Application This system can run on MS-DOS Prompt application from any windows system such as Windows XP, Windows ME etc. You must install and set up Microsoft Access database before run this system.

37. Steps: Step 1: Set up ODBC Data Source

38. Steps (cont.) Step 2: Start the Java application in MS-DOS Prompt console

39. Steps (cont.) Step 3: Enter the start URL and target topic in java application

40. Experiment Result : for target topic XML 1 st Iteration 2 nd Iteration 3 rd Iteration 4 th Iteration # of pages crawled2000300050007000 Candidate topics141167370398 Actual relevant topics25364557 Relevant topics by c=0.05524414651 False inclusion ( c=0.055)71060 False exclusion (c=0.055) 9556

41. Compared to Topic Expansion Algorithm, this system also has: Lower number of web pages crawled Other system : crawled 34,000 web pages to get 49 relevant topics out of 54 actual relevant topics Our system : crawled 17,000 web pages and get 51 relevant topics out of 57 actual relevant topics Don’t need a relation-based architecture Other system : most of them need a relationship-based hierarchy and update the hierarchy every time. Our system : Use stop word table instead

42. Conclusions Use early detection and data analysis techniques for detecting and analyzing candidate topics.  Improves crawl performance – visiting less number of web pages makes the system more efficient  Less human involvement - no need to create a relationship-based hierarchy

43. Future Work Adapt other character set such as Chinese,Korean, Japanese. Need to find a better way to detect the new born words and find their relevance to a specific topic.

44. Questions ?