September 15

September 15 - CSCI 2670 Introduction to Theory of...

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CSCI 2670 Introduction to Theory of Computing September 15, 2005
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Agenda •Yester day – Introduce context-free grammars •Today –No qu iz
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Context-free grammar definition A context-free grammar is a 4-tuple (V, Σ ,R,S), where 1. V is a finite set called the variables , 2. Σ is a finite set, disjoint from V, called the terminals , 3. R is a finite set of rules , with each rule being a variable and a string of variables and terminals, and 4. S V is the start variable .
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More definitions • If u, v, and w are strings of variables and terminals, and A w is a rule of the grammar, we say uAv yields uwv – Denoted uAv uwv • If a sequence of rules leads from u to v – i.e., u u 1 u 2 v, we denote this u * v • (I can’t do the actual notation in powerpoint – the * should be over the double bars) •The language of the grammar is {w ∈Σ * | s * w}
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This note was uploaded on 02/07/2011 for the course CS 501 taught by Professor Sm during the Spring '11 term at Indiana.

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September 15 - CSCI 2670 Introduction to Theory of...

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