September 21

September 21 - CSCI 2670 Introduction to Theory of...

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CSCI 2670 Introduction to Theory of Computing September 21, 2005
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September 23, 2004 2 Agenda •Yester day –Pushdown automata •Today –Qu
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September 23, 2004 3 Finite automata and PDA schematics State control FA a a b b State control PDA a a b b x y z Stack: Infinite LIFO (last in first out) device
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September 23, 2004 4 Definition of pushdown automaton A pushdown automaton is a 6-tuple (Q, Σ , Γ , δ ,q 0 ,F), where Q, Σ , Γ , and F are all finite sets, and 1. Q is the set of states 2. Σ is the input alphabet 3. Γ is the stack alphabet 4. δ : Q ×Σ ε ×Γ ε P (Q ×Γ ε ) is the transition function 5. q 0 Q is the start state, and 6. F Q are the accept states.
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September 23, 2004 5 Strings accepted by a PDA Let w be a string in Σ * and P a PDA. w is in L(P) iff w can be written w=w 1 w 2 …w n , where each w i ∈Σ ε , and there exist r 0 ,r 1 ,…,r n Qand±s 0 ,s 1 ,…,s n ∈Γ * satisfying
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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 21 - CSCI 2670 Introduction to Theory of...

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