Talk:Ogden's lemma
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[edit]What is "distinguished" ? The term is introduced in quotes, but it is not defined. Maybe I misunderstood? —Preceding unsigned comment added by 212.225.68.142 (talk • contribs) 11:45, 7 March 2006
- it means it's marked. maybe it will be clearer if I removed the word "distinguished" --Spoon! 02:37, 14 December 2006 (UTC)
- How is "marked" better than "distinguished"? They both need to be explained. Swapping one for another makes no difference.Wvxvw (talk) 12:11, 23 January 2016 (UTC)
- Two remarks.
- Ogden's Lemma still is not powerful enough to characterize the context-free languages. There are non-CF languages that pass Ogden's test.
- The example language given indeed satisfies the classical pumping lemma. An easy way to show its non-CF-ness is to intersect it with a properly chosen regular language (fixing the number od a's to 1) Jochgem 07:27, 13 April 2007 (UTC)