Google PageRank Formula: Changes Over Time - The Introduction of Topic Sensitive PageRank
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Topic-Sensitive PageRank is a theoretical attempt to make the system of PageRank potentially more accurate. Instead of a single PR ranking, the TSPR calculation would create several different PageRanks for each particular topic. The topics used for the tabulations would be representative of the theme of each specific web page.
The idea would be to use a number pre-calculated and topic-biased vectors to create a number of PageRanks for each web document. In that sense, the PR would be theme sensitive.
Instead of the PageRank being based on all incoming links, the Topic-Sensitive PageRank would be heavily weighted toward links that were related to the page’s main subject area. Links from sites not directly on topic with the specific web page would be assigned much less weight in the calculation.
In the Topic-Sensitive PageRank system, heavily linked pages bearing no informational relationship with the search term will be given less weight for that topic. On the other hand, pages receiving only a few incoming links, but from very related sites, will be given much more consideration for that term. The result will be a higher TSPR for that site, for that specific search query, despite a much lower PR under the current system.
Similar to the previously used Google PageRank system, the Topic-Sensitive PageRank might also be pre-computed, to save time in the search query processing. Since there are multiple themes to calculate, each page would be scored against multiple topics. Instead of one PR number, there would be many numbers based on the total number of themes used in the computation. That appears to many Google observers to be what is happening with PageRank calculations at the present time.
Keeping these additions to the original Google PageRank formula in mind, we have a much more complex system of calculations being utilized at the present time.
Next: A Theoretical Example >>
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