lect13-cfl4

# lect13-cfl4 - ThePumpingLemmafor CFLs Statement...

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1 The Pumping Lemma for  CFL’s Statement Applications

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2 Intuition Recall the pumping lemma for regular  languages. It told us that if there was a string long  enough to cause a cycle in the DFA for  the language, then we could “pump” the  cycle and discover an infinite sequence  of strings that had to be in the language.
3 Intuition – (2) For CFL’s the situation is a little more  complicated. We can always find  two  pieces of any  sufficiently long string to “pump” in  tandem. That is : if we repeat each of the two pieces  the same number of times, we get another  string in the language.

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Statement of the CFL Pumping  Lemma For every context-free language L    There is an integer n, such that       For every string z in L of length >  n          There exists z = uvwxy such that: 1. |vwx| <  n. 2.
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lect13-cfl4 - ThePumpingLemmafor CFLs Statement...

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