pumpinglemma2

pumpinglemma2 - s ∈ L where | s | ≥ p such that for all...

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Computer Science E-207 Pumping Lemma for Context-Free Languages Pumping Lemma for Context-Free Languages, Strong Version If G is a context-free grammar, then there exists a constant p such that, for every string s L ( G ), where | s | ≥ p , there exist strings u,v,x,y,z Σ * , where s = uvxyz , | vxy | ≤ p , and | vy | 6 = 0 such that, for all n 0, uv n xy n z L ( G ). To show that some language, L , is not context-free, you simply need show that. .. For all p 0, there exists some
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Unformatted text preview: s ∈ L , where | s | ≥ p , such that, for all u,v,x,y,z ∈ Σ * , where s = uvxyz , | vxy | ≤ p , and | vy | 6 = 0 there exists some n ≥ 0 such that uv n xy n z / ∈ L . In other words, cleverly choose some s ∈ L and show that, no matter how you choose vxy (and, in turn, u and z ), there’s always some n ≥ 0 for which uv n xy n z / ∈ L . 1...
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