Page Rank


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Its basically deals with how page ranking algorithm of Google works.

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  • Page Rank

    1. 1. PageRank™ : The Technology That Powers The World’s Fastest Search Engine
    2. 2. … ..And How It Can Be Used To Solve Real World Problems Pramit Kumar Computer Science Department, R.V.College of Engineering, Bangalore, India
    3. 3. Google Demystified……. <ul><li>Uncover the secrets of Google’s amazing speed and accuracy </li></ul><ul><li>What is PageRank </li></ul><ul><li>Why PageRank is a pioneering technology </li></ul><ul><li>How your search query travels through Google’s systems to give you results </li></ul><ul><li>How can PageRank be used in solving real world problems </li></ul>
    4. 4. Why is Google different ?
    5. 5. The First Search Engines <ul><li>Earlier engines relied on frequency of keywords only… </li></ul><ul><li>No. of times a term or query appeared on a page </li></ul><ul><li>Inefficient, low quality </li></ul><ul><li>Not Objective, not accurate, misleading </li></ul><ul><li>Not suitable for today’s thirst for distilled and crystallized information </li></ul>
    6. 6. … and Google <ul><li>Employed an innovative search technology called Page Rank. </li></ul><ul><li>Makes use of the link structure of the web </li></ul><ul><li>Objectively determines the importance of documents in a linked database. </li></ul>
    7. 7. A Breakthrough Technology <ul><li>PageRank relies on the uniquely democratic nature of the web </li></ul><ul><li>Using its vast link structure as an indicator of an individual page's value </li></ul><ul><li>PageRank is a method of assessing the importance of a web page based on its relationship to other web pages. </li></ul>
    8. 8. The Link Structure exploited
    9. 9. Democratic nature of PageRank A B B I Vote for B How many links or votes does a page receive Web page A Web page B A Link
    10. 10. … .but that’s not all A B B Web page A A Link Who is casting the vote. What is the PageRank of A ? IF A is an important page it helps to make B important too. Web page B
    11. 11. <ul><li>This is then combined with sophisticated text matching and content-based search techniques to find pages that are both important and relevant to one’s search. </li></ul>
    12. 12. Why popular <ul><li>Google’s PageRank technology makes use of the additional structure present in hypertext to provide much higher quality search </li></ul><ul><li>Google thus crawls the web and indexes the Web much more efficiently than existing systems </li></ul><ul><li>PageRank is calculated mathematically and withourt human interference. </li></ul><ul><li>Today PageRank has become a popular measurement standard for determining the value of a web site </li></ul><ul><li>Maps user behaviour </li></ul>
    13. 13. Random Surfer Model <ul><li>Assume there is a “random surfer” who is given a web page at random </li></ul><ul><li>He keeps clicking on links from one page to another, never hitting “back” </li></ul><ul><li>But eventually gets bored and starts on another random page </li></ul><ul><li>The probability that the random surfer visits a new page is the PageRank of the page. Thus it closely models user behavior. </li></ul>
    14. 14. How Google Calculates PageRank <ul><li>PR(A) = ( 1-d ) + d (PR(T1)/ C(T1) + ........ PR(Tn)/C(Tn)) </li></ul><ul><li>A PageRank for 26 million web pages  in a few hours on a medium size workstation. </li></ul><ul><li>The PageRanks form a normalised probability distribution over web pages </li></ul><ul><li>So the sum of all web pages’ PageRanks will be one </li></ul>
    15. 15. Intriguing ? <ul><li>How the PageRank values (which are order of a billionth fraction of one) are so drastically scaled to a factor between 0 and 10 </li></ul><ul><li>This information remains undisclosed by Google </li></ul><ul><li>However persistent research efforts have evidenced that the scaling is logarithmic </li></ul>
    16. 16. Parameters evaluated <ul><li>Right keyword queries </li></ul><ul><li>The relevance of the page. </li></ul><ul><li>First, it has location information for all hits and so it makes use of proximity in search. </li></ul><ul><li>Google keeps track of some visual presentation details such as font size of words. Words in a larger or bolder font are weighted higher than other words. </li></ul><ul><li>Google also uses anchor text. In addition to associating a link with the page that the link is on, it is also associated with the page the link points to. This ensures that documents like images, programs and databases are also indexed. </li></ul>
    17. 18. Applications for PageRank in solving real world problems
    18. 19. Some applications beyond Google <ul><li>Reputation Systems for ecommerce </li></ul><ul><li>Programmable networks </li></ul><ul><li>Dynamic Price Setting </li></ul><ul><li>Stock Market Trading </li></ul><ul><li>Collaborative Filtering </li></ul><ul><li>Opinion polls </li></ul><ul><li>Web information personalization </li></ul><ul><li>Web mining </li></ul><ul><li>Theme-based Ranking </li></ul><ul><li>Real world networks </li></ul><ul><li>Business Intelligence </li></ul>
    19. 20. References <ul><li>Sergey Brin and Lawrence Page, “Anatomy of a Large-Scale Hypertextual Web Search Engine” </li></ul><ul><li>Lawrence Page, Motwani, “ Bringing Order to the Web” </li></ul><ul><li>Andrew Clausen, “Online Reputation System: The Cost of Attack of PageRank” </li></ul><ul><li> </li></ul><ul><li> </li></ul>
    20. 21. <ul><li>…… .and that’s what is the secret behind Google </li></ul><ul><li>So did you today ? </li></ul>
    21. 22. Thank you Any Questions ??????