Pushdown Automaton: CFL and the pumping lemma
Pushdown Automaton: CFL and the pumping lemma
Pushdown Automaton: CFL and the pumping lemma
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The Pumping Lemma - background<br />
• Let L be a <strong>CFL</strong> <strong>and</strong> let G be a simple<br />
grammar (no unit/ rules) generating it.<br />
• Let wL be a long enough word (we will say<br />
later what is long).<br />
• The parsing tree of w contains a long path<br />
from S to some leaf (terminal).<br />
• On this long path some variable R must<br />
repeat (remember, w is long).<br />
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