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  2. Terminal and nonterminal symbols - Wikipedia

    en.wikipedia.org/wiki/Terminal_and_nonterminal...

    Terminal symbols are the elementary symbols of the language defined as part of a formal grammar. Nonterminal symbols (or syntactic variables) are replaced by groups of terminal symbols according to the production rules. The terminals and nonterminals of a particular grammar are in two completely separate sets.

  3. Context-free grammar - Wikipedia

    en.wikipedia.org/wiki/Context-free_grammar

    A nonterminal symbol is called productive, or generating, if there is a derivation for some string of terminal symbols. X {\displaystyle X} is called reachable if there is a derivation S ⇒ ∗ α X β {\displaystyle S{\stackrel {*}{\Rightarrow }}\alpha X\beta } for some strings α , β {\displaystyle \alpha ,\beta } of nonterminal and ...

  4. Noncontracting grammar - Wikipedia

    en.wikipedia.org/wiki/Noncontracting_grammar

    A context-sensitive grammar is a noncontracting grammar in which all rules are of the form αAβ → αγβ, where A is a nonterminal, and γ is a nonempty string of nonterminal and/or terminal symbols. However, some authors use the term context-sensitive grammar to refer to noncontracting grammars in general. [1]

  5. Formal grammar - Wikipedia

    en.wikipedia.org/wiki/Formal_grammar

    It also distinguishes a special nonterminal symbol, called the start symbol. The language generated by the grammar is defined to be the set of all strings without any nonterminal symbols that can be generated from the string consisting of a single start symbol by (possibly repeated) application of its rules in whatever way possible.

  6. Metasyntax - Wikipedia

    en.wikipedia.org/wiki/Metasyntax

    A terminal symbol, such as a word or a token, is a stand-alone structure in a language being defined. A nonterminal symbol represents a syntactic category, which defines one or more valid phrasal or sentence structure consisted of an n-element subset. Metasymbols provide syntactic information for denotational purposes in a given metasyntax.

  7. Unrestricted grammar - Wikipedia

    en.wikipedia.org/wiki/Unrestricted_grammar

    An unrestricted grammar is a formal grammar = (,,,), where . is a finite set of nonterminal symbols,; is a finite set of terminal symbols with and disjoint, [note 1]; is a finite set of production rules of the form , where and are strings of symbols in and is not the empty string, and

  8. Context-sensitive grammar - Wikipedia

    en.wikipedia.org/wiki/Context-sensitive_grammar

    Let us notate a formal grammar as = (,,,), with a set of nonterminal symbols, a set of terminal symbols, a set of production rules, and the start symbol.. A string () directly yields, or directly derives to, a string (), denoted as , if v can be obtained from u by an application of some production rule in P, that is, if = and =, where () is a production rule, and , is the unaffected left and ...

  9. Chomsky normal form - Wikipedia

    en.wikipedia.org/wiki/Chomsky_normal_form

    where A, B, and C are nonterminal symbols, the letter a is a terminal symbol (a symbol that represents a constant value), S is the start symbol, and ε denotes the empty string. Also, neither B nor C may be the start symbol, and the third production rule can only appear if ε is in L(G), the language produced by the context-free grammar G.