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  2. Inverted index - Wikipedia

    en.wikipedia.org/wiki/Inverted_index

    The purpose of an inverted index is to allow fast full-text searches, at a cost of increased processing when a document is added to the database. [2] The inverted file may be the database file itself, rather than its index. It is the most popular data structure used in document retrieval systems, [3] used on a large scale for example in search ...

  3. Question answering - Wikipedia

    en.wikipedia.org/wiki/Question_answering

    Once the system identifies the question type, it uses an information retrieval system to find a set of documents that contain the correct keywords. A tagger and NP/Verb Group chunker can verify whether the correct entities and relations are mentioned in the found documents.

  4. Information retrieval - Wikipedia

    en.wikipedia.org/wiki/Information_retrieval

    1983: Salton (and Michael J. McGill) published Introduction to Modern Information Retrieval (McGraw-Hill), with heavy emphasis on vector models. 1985: David Blair and Bill Maron publish: An Evaluation of Retrieval Effectiveness for a Full-Text Document-Retrieval System mid-1980s: Efforts to develop end-user versions of commercial IR systems.

  5. Search algorithm - Wikipedia

    en.wikipedia.org/wiki/Search_algorithm

    Visual representation of a hash table, a data structure that allows for fast retrieval of information In computer science , a search algorithm is an algorithm designed to solve a search problem . Search algorithms work to retrieve information stored within particular data structure , or calculated in the search space of a problem domain, with ...

  6. Document retrieval - Wikipedia

    en.wikipedia.org/wiki/Document_retrieval

    Document retrieval is defined as the matching of some stated user query against a set of free-text records. These records could be any type of mainly unstructured text, such as newspaper articles, real estate records or paragraphs in a manual.

  7. Search engine indexing - Wikipedia

    en.wikipedia.org/wiki/Search_engine_indexing

    Stores citations or hyperlinks between documents to support citation analysis, a subject of bibliometrics. n-gram index Stores sequences of length of data to support other types of retrieval or text mining. [13] Document-term matrix Used in latent semantic analysis, stores the occurrences of words in documents in a two-dimensional sparse matrix.

  8. Vector space model - Wikipedia

    en.wikipedia.org/wiki/Vector_space_model

    Candidate documents from the corpus can be retrieved and ranked using a variety of methods. Relevance rankings of documents in a keyword search can be calculated, using the assumptions of document similarities theory, by comparing the deviation of angles between each document vector and the original query vector where the query is represented as a vector with same dimension as the vectors that ...

  9. Okapi BM25 - Wikipedia

    en.wikipedia.org/wiki/Okapi_BM25

    The fuller name, Okapi BM25, includes the name of the first system to use it, which was the Okapi information retrieval system, implemented at London's City University [1] in the 1980s and 1990s. BM25 and its newer variants, e.g. BM25F (a version of BM25 that can take document structure and anchor text into account), represent TF-IDF -like ...