Controlled natural languages (CNLs) are subsets of natural languages that are obtained by restricting the grammar and vocabulary in order to reduce or eliminate ambiguity 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 semantic analysis of the language.
The first type of languages (often called "simplified" or "technical" languages), for example ASD Simplified Technical English, Caterpillar Technical English, IBM's Easy English, are used in the industry to increase the quality of technical documentation, and possibly simplify the semi-automatic translation of the documentation. These languages restrict the writer by general rules such as "Keep sentences short", "Avoid the use of pronouns", "Only use dictionary-approved words", and "Use only the active voice".
The second type of languages have a formal syntax and semantics, and can be mapped to an existing formal language, such as first-order logic. Thus, those languages can be used as knowledge representation languages, and writing of those languages is supported by fully automatic consistency and redundancy checks, query answering, etc.
- ASD Simplified Technical English
- Attempto Controlled English
- Aviation English
- Basic English
- Common Logic Controlled English
- Distributed Language Translation Esperanto
- Français fondamental
- Gellish Formal English
- Interlingua-IL sive Latino sine flexione (Giuseppe Peano)
- Processable English (PENG)
- Semantics of Business Vocabulary and Business Rules
- Special English
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