These lectures are very helpful and easy to understand. Please upgrade the video quality!
@iam_subh5035
8 жыл бұрын
Perhaps the best explanation of pumping lemma.. Thanks a lot.
@sneh9817
6 жыл бұрын
Attention! In case 1 itself your vxy exceeds your pumping length. Can we contradict the basic condition to prove something by contradiction? lol I mean could we completely ignore the conditions |vy|>0 and |vxy|
@preetomsahaarko8145
8 жыл бұрын
In the NOT-PUMPING PROPERTY, shouldn't it be like "u v^i x y^i z doesn't belong to L for SOME i>=0" ( in the video we see "for ALL i>=0" ). When we use the pumping lemma, we always try to find just a single counterexample of i for which u v^i x y^i z doesn't belong to L. As we see the case of both pumping up and pumping down in some examples, sometimes "pumping up" preserves the pumping property, but "pumping down" doesn't.
@WowPlusWow
4 жыл бұрын
Yes , you are correct.
@53540000
8 жыл бұрын
Excellent explanation, really wish you are my professor
@kwask
3 жыл бұрын
Low quality footage, high quality teacher!
@chii_nik
7 жыл бұрын
the best tutorial out there. Thank you
@nkuguy
8 жыл бұрын
I really like this explanation of building a proof by contradiction.
@MomentsOfMelody
9 жыл бұрын
Very good explanation. But I just wonder, why sometimes you used "pumping up" and sometimes "pumping down"?
@zhijuyang9298
8 жыл бұрын
@hhp3, Does case 1 showed in 30.:00 have some problems? because if left out all "b"s as x, then your |vxy| will greater than p, that doesn't satisfy pumping lemma. Am I right, plz?
@Liaomiao
4 жыл бұрын
Is there a reason why you chose to pump down instead of up and vice versa at times? It would have worked either way right?
@WowPlusWow
4 жыл бұрын
Yes, but you may find an i that actually belongs in the language. For example, choosing i = 1 in his example would have resulted in a string that belongs in the language. If this occurs, just pick another i and once you found an i that causes the string to not belong in the language, then you proved the language is not context-free by contradiction. :)
@יוסיבכר-ע3י
7 жыл бұрын
at 31:11 seems theres a problem in the example you chose vxy that their length is bigger than p
@fardadhajirostami7104
7 жыл бұрын
THIS
@sneh9817
6 жыл бұрын
Exactly. Why is nobody asking? Are we the only dumb guys here?
@aaronweiss3294
5 жыл бұрын
He mentions at the end of the example that the other conditions may be violated as well, and could be used to show that the division of the word where v and y include "a"s and "c"s respectively, but there's no need too use that condition as even without using it we've shown the language is not context free
@JurajNyiri
9 жыл бұрын
Awesome video, but the quality of resolution is really bad :( Anyway, thank you for a very well made learning material.
@Duffmanjack
8 жыл бұрын
Great videos, thanks for uploading
@igniculus_
7 жыл бұрын
your videos are amazing ... I wish video quality was better ...
@gerhardtfunk4463
4 жыл бұрын
Very nice but there's one thing I'm unclear about. DO WE KNOW WHAT P IS???
@Suav58
4 жыл бұрын
P is alphabet dependent. To know what p is you'd have to know both the rules set and the alphabet set. Every finite subset of a language (finite subset of strings in a given alphabet) can be trivially represented by regular expressions (just expand the alphabet). This alphabet can be reduced then, by applying some CFG. Going further, one can make some practical deductions about the nature of processes at hand by estimation of both storage space and computational power of the device.
@goldfish8196
8 жыл бұрын
Great explanation. Thank you.
@pengqianlu6824
6 жыл бұрын
Thank you ~
@fcurdi
5 жыл бұрын
Amazing video, super clear. The quality pretty bad though
@hhp3
5 жыл бұрын
Thanks!
@ryans6423
6 жыл бұрын
These lectures are great but they'd be 30x better if you were to watch the video after you record it and rewrite your train of thought when teaching them and record it again more fluidly. You jump around a lot and you can tell that you forget where you were going and then start explaining something else and that's where I lose you. Just put a bit more effort into how you fluidly explain the train of thought needed to understand this concepts and to go through these problems. It would also make these videos sooo much shorter than they are.
@hhp3
6 жыл бұрын
Ryan Sloop, please forward me a link to an original multi-hour video series on a graduate-level scientific theory topic that YOU HAVE PRODUCED, so I can see how it should be done right. Until then, remember rule #1: "Don't complain, criticize, or condemn."
@InfiniteDesign91
5 жыл бұрын
I think this video is very clear and understandable. My teachers at the the university I attend, could explain pumping lemmas in a very confusing way. The jumping to the logic part was good. DR hhp3 gives reminders of other topics, that are necessary to understand the actual topic. I really like this, because the other teachers at the university usually omit prerequisites and conveniently respond with "you should already know that". hhp3 lectures with giving all the necessary other topics like how to prove something indirectly. Only complaint could be image quality but so far it is readable so it's okay. It is quality content.
@Suav58
4 жыл бұрын
@@hhp3 This is not a rule of scientific discourse but one of political correctness... This is not how the science was built. In fact, it can be traced to some dark periods in the history of science. (and some rules of scientifically based dydactics seem to be emerging)
@lonnybulldozer8426
3 жыл бұрын
@@hhp3 Very funny. Way to put Ryan Sloop in his place.
@abhishekmazumdar2072
3 жыл бұрын
Horrible camera. Such a shame. I really like the coursework. But the video is a pain.
@Manuelruizju
7 жыл бұрын
There is a copy of your vid with 11k views! Report it!
@shaunmike
9 жыл бұрын
I'm really learning from these, but I think you mislabeled this video.
@paranjsoni8234
8 жыл бұрын
Terrible explanation.
@georgecernat6166
8 жыл бұрын
how come?
@adrianliu3577
7 жыл бұрын
Are you serious?
@inowhy1930
7 жыл бұрын
I think he was expecting a Movie Trailer for the Pumping Lemma for Context Free Languages *badum tsss*
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