September 14

September 14 - CSCI 2670 Introduction to Theory of...

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CSCI 2670 Introduction to Theory of Computing September 14, 2005
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Agenda Yesterday Pumping lemma  Today Introduce context-free grammars Formally define CFG’s Begin designing CFG’s Tomorrow More on designing CFG’s Chomsky normal form
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Announcement Quiz tomorrow Regular expressions Pumping lemma
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Context-free grammars The shortcoming of finite automata is that each  state has very limited meaning You have no memory of where you’ve been – only  knowledge of where you are Context-free grammars are a more powerful  method of describing languages Example: {0 n 1 n  | n   0} is a CFG
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Example CFG Context-free grammars use substitution to  maintain knowledge  (S)  SS  () All possible legal parenthesis pairings can be  expressed by consecutive applications of these rules Is this a regular language?
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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 14 - CSCI 2670 Introduction to Theory of...

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