{"id":158,"date":"2007-06-03T14:20:43","date_gmt":"2007-06-03T18:20:43","guid":{"rendered":"http:\/\/mat.tepper.cmu.edu\/blog\/?p=149"},"modified":"2007-06-03T14:20:43","modified_gmt":"2007-06-03T18:20:43","slug":"googles-search-algorithm","status":"publish","type":"post","link":"https:\/\/mat.tepper.cmu.edu\/blog\/index.php\/2007\/06\/03\/googles-search-algorithm\/","title":{"rendered":"Google\u2019s search algorithm"},"content":{"rendered":"

There is an article in the New York Times<\/em> on Google’s algorithm for returning pages after a search<\/a>. It is remarkable how complex it has become. At its base is a concept called Page Rank (named after Larry Page, one of the founders of Google), a very simple concept that every operations research student can understand (Wikipedia has a short outline of it<\/a>). You can see Page Rank as the ergodic state of a markov chain, or as an eigenvector of a particular matrix (as described by Kurt Bryan and Tanya Leise<\/a>).\u00a0 But the system has gone far beyond that:<\/p>\n

Mr. Singhal [the subject of the article;\u00a0 the Google engineer responsible for the rankings] has developed a far more elaborate system for ranking pages, which involves more than 200 types of information, or what Google calls \u201csignals.\u201d PageRank is but one signal. Some signals are on Web pages \u2014 like words, links, images and so on. Some are drawn from the history of how pages have changed over time. Some signals are data patterns uncovered in the trillions of searches that Google has handled over the years.<\/p>\n

\u201cThe data we have is pushing the state of the art,\u201d Mr. Singhal says. \u201cWe see all the links going to a page, how the content is changing on the page over time.\u201d<\/p>\n

Increasingly, Google is using signals that come from its history of what individual users have searched for in the past, in order to offer results that reflect each person\u2019s interests. For example, a search for \u201cdolphins\u201d will return different results for a user who is a Miami football fan than for a user who is a marine biologist. This works only for users who sign into one of Google\u2019s services, like Gmail.<\/p><\/blockquote>\n

Lots of operations research projects end up looking like that.\u00a0 A sharp, clean model at the core, augmented over time with more and more additions to better fit reality.<\/p>\n","protected":false},"excerpt":{"rendered":"

There is an article in the New York Times on Google’s algorithm for returning pages after a search. It is remarkable how complex it has become. At its base is a concept called Page Rank (named after Larry Page, one of the founders of Google), a very simple concept that every operations research student can … Continue reading “Google\u2019s search algorithm”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,39],"tags":[],"class_list":["post-158","post","type-post","status-publish","format-standard","hentry","category-applications","category-or-in-the-press"],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/mat.tepper.cmu.edu\/blog\/index.php\/wp-json\/wp\/v2\/posts\/158","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mat.tepper.cmu.edu\/blog\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mat.tepper.cmu.edu\/blog\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mat.tepper.cmu.edu\/blog\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mat.tepper.cmu.edu\/blog\/index.php\/wp-json\/wp\/v2\/comments?post=158"}],"version-history":[{"count":0,"href":"https:\/\/mat.tepper.cmu.edu\/blog\/index.php\/wp-json\/wp\/v2\/posts\/158\/revisions"}],"wp:attachment":[{"href":"https:\/\/mat.tepper.cmu.edu\/blog\/index.php\/wp-json\/wp\/v2\/media?parent=158"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mat.tepper.cmu.edu\/blog\/index.php\/wp-json\/wp\/v2\/categories?post=158"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mat.tepper.cmu.edu\/blog\/index.php\/wp-json\/wp\/v2\/tags?post=158"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}