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Controlled natural language
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<p>Controlled natural languages (CNLs) are subsets of <a href="/facts/Natural_language/B4gLS7Kd">natural languages</a> that are obtained by restricting the grammar and vocabulary in order to reduce or eliminate <a href="/facts/Ambiguity/mgn4oEoQ">ambiguity</a> and complexity. Traditionally, controlled languages fall into two major types: those that improve readability for human readers (e.g. non-native speakers), and those that enable reliable automatic <a href="/facts/Semantic_analysis_(linguistics)/vVT2PADY">semantic analysis</a> of the language. </p><p>The first type of languages (often called "simplified" or "technical" languages), for example <a href="/facts/ASD_Simplified_Technical_English/PyHCaL4b">ASD Simplified Technical English</a>, Caterpillar Technical English, <a href="/facts/IBM/QszA7nwd">IBM</a>'s Easy English, are used in the industry to increase the quality of technical documentation, and possibly simplify the <a href="/facts/Computer-assisted_translation/JHebmnfD">semi-automatic translation</a> of the documentation. These languages restrict the writer by general rules such as "Keep sentences short", "Avoid the use of <a href="/facts/Pronoun/UsbSNRSl">pronouns</a>", "Only use dictionary-approved words", and "Use only the <a href="/facts/Active_voice/JlJ4yevg">active voice</a>". </p><p>The second type of languages have a formal syntax and <a href="/facts/Formal_semantics_(natural_language)/FlWb7Hxp">formal semantics</a>, and can be mapped to an existing <a href="/facts/Formal_language/crDTyP8q">formal language</a>, such as <a href="/facts/First-order_logic/lcISqWIg">first-order logic</a>. Thus, those languages can be used as <a href="/facts/Knowledge_representation_language/cDPkIaKf">knowledge representation languages</a>, and writing of those languages is supported by fully automatic <a href="/facts/Consistency/IHkdnA9M">consistency</a> and redundancy checks, <a href="/facts/Query_answering/1gplmc6L">query answering</a>, etc. </p>