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Google- opoly

Google- opoly. Amy N. Langville Mathematics Department College of Charleston langvillea@cofc.edu. Math Meet 2/20/10. Outline. Short History of Web Search Link Analysis and Google’s PageRank The Random Surfer Google-opoly March Madness Conclusion. Thesis. 1998.

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Google- opoly

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  1. Google-opoly Amy N. Langville Mathematics Department College of Charleston langvillea@cofc.edu Math Meet 2/20/10

  2. Outline • Short History of Web Search • Link Analysis and Google’s PageRank • The Random Surfer • Google-opoly • March Madness • Conclusion

  3. Thesis 1998 Mathematics transformed web search.

  4. Pre-1998 Web • Trip back in time to 1995 • How did you find information then?

  5. Pre-1998 Web • Trip back in time to 1995 • How did you find information then? • Better question:

  6. Pre-1998 Web • Trip back in time to 1995 • How did you find information then? • Better question: how old were you then?

  7. Pre-1998 Web • Trip back in time to 1995 • How did you find information then? • Better question: how old were you then?

  8. Inverted Index Main tool of pre-1998 search engines

  9. Problems with the Inverted Index • Too many pages

  10. Problems with the Inverted Index • Too many pages • Spam

  11. Problems with the Inverted Index • Too many pages • Spam: human eyes vs. spider eyes

  12. Problems with the Inverted Index • Too many pages • Spam: human eyes vs. spider eyes

  13. Problems with the Inverted Index • Too many pages • Spam: human eyes vs. spider eyes

  14. Problems with the Inverted Index • Too many pages • Spam: human eyes vs. spider eyes Win a ipod Learn how to make millions Text 8 if you’re awake

  15. Link Analysis 1998 text analysis Link analysis • pre-1998 engines only used text analysis. • Link analysis saved search from SEOs and • built companies like Google, Yahoo, Ask. • Nearly every major search engine uses • link analysis.

  16. Link Analysis 1998 text analysis Link analysis • pre-1998 engines only used text analysis. • Link analysis saved search from SEOs and • built companies like Google, Yahoo, Ask. • Nearly every major search engine uses • link analysis.

  17. Moral #1 Sometimes being perceived as an expert forces you to become one.

  18. What happens when you google? All the old text analysis + the new link analysis

  19. What happens when you google? ranked list 1 2 3 4 5 6 7 8

  20. Why are rankings so important?

  21. Web as a graph • Each node is a webpage. • Each arrow is a hyperlink.

  22. In-links vs. Out-links • In-links are votes of endorsement from one page to another.

  23. A Trip to Google-topia • Emmie • Randy, the Random Surfer video clip

  24. A Random Walk on the Web graph

  25. Matrix Notation

  26. BUT THERE ARE SOME PROBLEMS!

  27. The surfer gets stuck! • This is called a dangling node. • How does Google fix this?

  28. The surfer can “teleport” • We add a link from the dangling node to every other node. • When web surfing, this is equivalent to typing an address in the URL bar.

  29. Probability Matrix • We must also take this into consideration for our probability matrix.

  30. Dangling nodes and teleportation video clip

  31. Let’s look at another problem.

  32. Our surfer gets stuck in the webpages 4, 5, and 6. • This is called a cycle. • How do we fix this?

  33. Cycling video clip

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