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  2. Ranking (information retrieval) - Wikipedia

    en.wikipedia.org/wiki/Ranking_(information...

    Ranking of query is one of the fundamental problems in information retrieval (IR), [1] the scientific/engineering discipline behind search engines. [2] Given a query q and a collection D of documents that match the query, the problem is to rank, that is, sort, the documents in D according to some criterion so that the "best" results appear early in the result list displayed to the user.

  3. Discounted cumulative gain - Wikipedia

    en.wikipedia.org/wiki/Discounted_cumulative_gain

    Cumulative Gain is the sum of the graded relevance values of all results in a search result list. CG does not take into account the rank (position) of a result in the result list. The CG at a particular rank position is defined as: = = Where is the graded relevance of the result at position . The value computed with the CG function is ...

  4. Learning to rank - Wikipedia

    en.wikipedia.org/wiki/Learning_to_rank

    Recently they have also sponsored a machine-learned ranking competition "Internet Mathematics 2009" [56] based on their own search engine's production data. Yahoo has announced a similar competition in 2010. [57] As of 2008, Google's Peter Norvig denied that their search engine exclusively relies on machine-learned ranking. [58]

  5. Okapi BM25 - Wikipedia

    en.wikipedia.org/wiki/Okapi_BM25

    In information retrieval, Okapi BM25 (BM is an abbreviation of best matching) is a ranking function used by search engines to estimate the relevance of documents to a given search query. It is based on the probabilistic retrieval framework developed in the 1970s and 1980s by Stephen E. Robertson , Karen Spärck Jones , and others.

  6. Probabilistic relevance model - Wikipedia

    en.wikipedia.org/wiki/Probabilistic_relevance_model

    The probabilistic relevance model [1] [2] was devised by Stephen E. Robertson and Karen Spärck Jones as a framework for probabilistic models to come. It is a formalism of information retrieval useful to derive ranking functions used by search engines and web search engines in order to rank matching documents according to their relevance to a given search query.

  7. Evaluation measures (information retrieval) - Wikipedia

    en.wikipedia.org/wiki/Evaluation_measures...

    Indexing and classification methods to assist with information retrieval have a long history dating back to the earliest libraries and collections however systematic evaluation of their effectiveness began in earnest in the 1950s with the rapid expansion in research production across military, government and education and the introduction of computerised catalogues.

  8. List of search engines - Wikipedia

    en.wikipedia.org/wiki/List_of_search_engines

    Cross-platform open-source desktop search engine. Unmaintained since 2011-06-02 [9]. LGPL v2 [10] Terrier Search Engine: Linux, Mac OS X, Unix: Desktop search for Windows, Mac OS X (Tiger), Unix/Linux. MPL v1.1 [11] Tracker: Linux, Unix: Open-source desktop search tool for Unix/Linux GPL v2 [12] Tropes Zoom: Windows: Semantic Search Engine (no ...

  9. PageRank - Wikipedia

    en.wikipedia.org/wiki/PageRank

    A search engine called "RankDex" from IDD Information Services, designed by Robin Li in 1996, developed a strategy for site-scoring and page-ranking. [15] Li referred to his search mechanism as "link analysis," which involved ranking the popularity of a web site based on how many other sites had linked to it. [16] RankDex, the first search ...