Exercise on pumping lemma Ch7_II slide 17

Exercise on pumping lemma Ch7_II slide 17

by ABDELRAHMAN ASHRAF MAHMOUD HASSAN -
Number of replies: 1

Hello everyone, just a QQ: in a CFL pumping lemma proof, if one of the possible cases for where vwx is placed already breaks the language after pumping, is that sufficient, or do we still need to analyze all other cases?


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In reply to ABDELRAHMAN ASHRAF MAHMOUD HASSAN

Re: Exercise on pumping lemma Ch7_II slide 17

by ALVISE GARBERINO -
To prove a language is not context-free using the pumping lemma you must show that every possible decomposition allowed by the lemma fails (i.e., for each decomposition there is some k for which the pumped string is not in the language).