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2. Context-free grammar - Wikipedia

   en.wikipedia.org/wiki/Context-free_grammar

   An extended context-free grammar (or regular right part grammar) is one in which the right-hand side of the production rules is allowed to be a regular expression over the grammar's terminals and nonterminals. Extended context-free grammars describe exactly the context-free languages.

3. Context-free language - Wikipedia

   en.wikipedia.org/wiki/Context-free_language

   The set of all context-free languages is identical to the set of languages accepted by pushdown automata, which makes these languages amenable to parsing.Further, for a given CFG, there is a direct way to produce a pushdown automaton for the grammar (and thereby the corresponding language), though going the other way (producing a grammar given an automaton) is not as direct.

4. Greibach normal form - Wikipedia

   en.wikipedia.org/wiki/Greibach_normal_form

   Some do not permit the second form of rule and cannot transform context-free grammars that can generate the empty word. For one such construction the size of the constructed grammar is O(n 4) in the general case and O(n 3) if no derivation of the original grammar consists of a single nonterminal symbol, where n is the size of the original ...

5. Formal grammar - Wikipedia

   en.wikipedia.org/wiki/Formal_grammar

   The difference between these types is that they have increasingly strict production rules and can therefore express fewer formal languages. Two important types are context-free grammars (Type 2) and regular grammars (Type 3). The languages that can be described with such a grammar are called context-free languages and regular languages ...

6. Generative grammar - Wikipedia

   en.wikipedia.org/wiki/Generative_grammar

   Generative grammar is a research tradition in ... because English imperative tag ... many of which are modifications or extensions of context free ...

7. Chomsky normal form - Wikipedia

   en.wikipedia.org/wiki/Chomsky_normal_form

   Every grammar in Chomsky normal form is context-free, and conversely, every context-free grammar can be transformed into an equivalent one [note 1] which is in Chomsky normal form and has a size no larger than the square of the original grammar's size.

8. Synchronous context-free grammar - Wikipedia

   en.wikipedia.org/wiki/Synchronous_context-free...

   Synchronous context-free grammars (SynCFG or SCFG; not to be confused with stochastic CFGs) are a type of formal grammar designed for use in transfer-based machine translation. Rules in these grammars apply to two languages at the same time, capturing grammatical structures that are each other's translations.

9. Context-sensitive grammar - Wikipedia

   en.wikipedia.org/wiki/Context-sensitive_grammar

   A context-sensitive grammar (CSG) is a formal grammar in which the left-hand sides and right-hand sides of any production rules may be surrounded by a context of terminal and nonterminal symbols. Context-sensitive grammars are more general than context-free grammars , in the sense that there are languages that can be described by a CSG but not ...