Notes-SecA-Fall06 - Let G =(N Σ P S be a psg Then the...

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Phrase Structure Grammars and the Chomsky Hierarchy Dr. David A. Workman School of EE and CS May 22, 2006
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Phrase Structure Grammar Definition. A phrase structure grammar (psg) is a 4-tuple, G = (N, Σ , P, S), where N = nonterminal alphabet Σ = terminal alphabet // N Σ = Φ leftpart rightpart A psg really is a "program" describing an algorithm for generating a language over the terminal alphabet, Σ ; that is, L(G) Σ *. To formalize this statement, we define a relation, G , from V* to V* defined by G. Specifically,
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Language defined by G Definition.
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Unformatted text preview: Let G = (N, Σ , P, S) be a psg. Then the language generated by G The Chomsky Hierarchy of Languages Type-0 Languages (Recursively Enum.) Recursive Languages Type-1 (Context-sensitive) Languages Type-2 (Context-free) Languages Type-3 (Regular) Languages Linear (Context-free) Languages Technical Note: Type-1 languages explicitly exclude the null string. All other language families permit the null string as a member. (The Venn diagram is in slight error because of this technicality.)...
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Notes-SecA-Fall06 - Let G =(N Σ P S be a psg Then the...

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