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Syntactic parsing (computational linguistics)
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<p>Syntactic parsing is the automatic analysis of <a href="/facts/Syntax/6PxSV98p">syntactic structure</a> of natural language, especially syntactic relations (in <a href="/facts/Dependency_grammar/cWnwcCM0">dependency grammar</a>) and labelling spans of constituents (in <a href="/facts/Constituency_grammar/SbzQXRFM">constituency grammar</a>). It is motivated by the problem of <a href="/facts/Structural_ambiguity/xPxLnwxt">structural ambiguity</a> in natural language: a sentence can be assigned multiple grammatical parses, so some kind of knowledge beyond computational grammar rules is needed to tell which parse is intended. Syntactic parsing is one of the important tasks in <a href="/facts/Computational_linguistics/XmegJ6LC">computational linguistics</a> and <a href="/facts/Natural_language_processing/1hjMKsSN">natural language processing</a>, and has been a subject of research since the mid-20th century with the advent of computers. </p><p>Different theories of grammar propose different formalisms for describing the syntactic structure of sentences. For computational purposes, these formalisms can be grouped under <a href="/facts/Constituency_grammar/SbzQXRFM">constituency grammars</a> and <a href="/facts/Dependency_grammar/cWnwcCM0">dependency grammars</a>. Parsers for either class call for different types of algorithms, and approaches to the two problems have taken different forms. The creation of human-annotated <a href="/facts/Treebank/7UNxE8Uw">treebanks</a> using various formalisms (e.g. <a href="/facts/Universal_Dependencies/LYlMsbqp">Universal Dependencies</a>) has proceeded alongside the development of new algorithms and methods for parsing. </p><p><a href="/facts/Part-of-speech_tagging/BYAPmH3r">Part-of-speech tagging</a> (which resolves some semantic ambiguity) is a related problem, and often a prerequisite for or a subproblem of syntactic parsing. Syntactic parses can be used for <a href="/facts/Information_extraction/DL9nMD2X">information extraction</a> (e.g. event parsing, semantic role labelling, entity labelling) and may be further used to extract <a href="/facts/Semantic_parsing/VEwJ18nL">formal semantic representations</a>. </p>