I've read the textbook for a couple of times, and I got to say that the concepts were rather complicated and abstract for me to comprehend. But thanks to the video which you made, it's very clear and now I know how it works and successfully linked most of the concepts on the textbook. Really appreciate it!
generally find Neso Academy videos quite useful because of the provision of practical examples to back up the theory... but like others this video left me scratching my head, and no better able to convert CFGs to PDAs than before i watched. a shame, especially as the video was 22 minutes long!
@@vaibhavbiradar9451 Seriously... These videos are free and incredible helpful and people complain because they have to watch 2 of them... Entitled and ungrateful people.
From lecture 80, we know that upper case sigma represents a finite set of input symbols and uppercase gamma represents a finite stack alphabet. They are two different sets. Can we say that uppercase sigma is the set of terminal symbols and uppercase gamma is the set of both terminal and non-terminal symbols?
Upper case gamma is the set of stack symbols/alphabets. As we know stack symbols can either be terminal or non terminal. However upper case sigma is set of input symbols only which are always terminals. So your statement is right but you need to indicate that sigma is for input symbols while gamma is for stack symbols. This is my understanding. Open to corrections.
one of the things i don't understand is that what if the production is of type B -> ACD | EF; which one to push , we need to apply recursion using stack . please further make a video explaiing how to perform recursion using stack.
It's a non-deterministic algorithm, so it will have multiple runs trying out different rules. It simply tests for if one of the runs evaluates to the given input.
left most derivation means that we have to take left most variable and change it, not take the left most value of the left most variable in the derivation. Hope it helps!
@@anushkagarhawal6918 to find a corresponding PDA, for a given grammar we must have to consider all possible cases. In other words, all possible strings obtained by productions rules must be accepted by PDA. So to obtain each possible combination of strings that must be accepted, we are first using those production which involves more no. Of non-terminals symbols and then using production that involves terminal symbols. Hope, you got that...!
@Mohd Sharique Alam, please refer to my comment above. Then coming to your question, as you have seen in that video, that whenever we have a terminal symbol in the top-most stack we just advance the Input symbol, till a non-terminal symbol. Since 'A' can have two productions, either string "0A" or ''epsilon". Now consider the case A->0A, so A is replaced by 0A in the top-most stack. Now we have '0' in the top-most stack which is a terminal symbol, so we will advance the string and (0, epsilon-->epsilon), and now the top-most symbol is again ''A", so using this production rule( A->0A ), we didn't get anything fruitful even we have make this PDA construction more complex. I hope, I got there...!
Because that production gives you two options, A->€ and A->0A. In that example, he wanted to look the most left derivation for the string 221. If you want to get the most left derivation for the string 2210, in that step you have to choose that option (A->0A) and then transform the non-terminal A to €.
Hi, I have a question I really urgently (like within a few a hours!) need an answer to: can you please explain why at 5:48 it doesn't become 2210A, then 2210? Am I missing something? I know some other people also wanted to know this answer. Thanks
I m having a doubt, what if our production going like this A --> Aa | Yb When PDA find non terminal A on top of stack then it would always took Aa not Yb. How we can solve it ?
19:14, the 0102 on input matches the 0102 on stack, but what would happen if 0103 is on input and 0102 is on stack? Seems this branch of logic is not explained... any help?
All the different rules are different examples he has taken to show the working of the method, I got confused if they were relating to the grammar in the start of the video
Don't panic to see the comments that some students can't understand it , actually this topic is little bit complex, so you have to see the video twice or thrice for proper understanding 👍
Is there more than one PDA corresponding to the same CFG. For example, in lecture 81, You give an PDA for strings 0^n1^n, we know the CFG for these strings is X->0X1. If we use this CFG to derive the PDA, it is different from the one in lecture 81. How can we prove that these two PDA are the same? Or how can we simplify the derived PDA to the one introduced in lecture 81?
I usually have no problems understanding your videos, but this one had me yawning all over. Jesus, I just want to graduate
Tell ur jeSUS to teach from cross😂
Only god knows where I will be applying this logic.
in your UTs or end Sem exams
To assert dominance in front of your friends
🤣😂😂
@@aryaman_godara 🤓
I also thought
I've read the textbook for a couple of times, and I got to say that the concepts were rather complicated and abstract for me to comprehend. But thanks to the video which you made, it's very clear and now I know how it works and successfully linked most of the concepts on the textbook. Really appreciate it!
generally find Neso Academy videos quite useful because of the provision of practical examples to back up the theory... but like others this video left me scratching my head, and no better able to convert CFGs to PDAs than before i watched. a shame, especially as the video was 22 minutes long!
I understood completely on the other hand.
f**k you dont make others feel dumb@@user-kt3mb8ug8r
for the first time i was disappointed at the end of the video for this channel
Sir please give an example. Of this type of questions we understand the method but doesn't know how to apply
2210A?
Literally no video on youtube starts with an example and finishes the same example. Just show and finish ONE example please for the love of jesus
All teacher are stupid
be grateful for what you are getting.
@Vaibhav Biradar fuck you
@@vaibhavbiradar9451 Seriously... These videos are free and incredible helpful and people complain because they have to watch 2 of them... Entitled and ungrateful people.
@@griffin3706 Nah, I’m good..your sister already did.
From lecture 80, we know that upper case sigma represents a finite set of input symbols and uppercase gamma represents a finite stack alphabet. They are two different sets. Can we say that uppercase sigma is the set of terminal symbols and uppercase gamma is the set of both terminal and non-terminal symbols?
Upper case gamma is the set of stack symbols/alphabets. As we know stack symbols can either be terminal or non terminal. However upper case sigma is set of input symbols only which are always terminals. So your statement is right but you need to indicate that sigma is for input symbols while gamma is for stack symbols. This is my understanding. Open to corrections.
Thanks a lot for your response.
Thanks you bro for clarifying @@yingma6770
one of the things i don't understand is that what if the production is of type B -> ACD | EF; which one to push , we need to apply recursion using stack . please further make a video explaiing how to perform recursion using stack.
It's a non-deterministic algorithm, so it will have multiple runs trying out different rules. It simply tests for if one of the runs evaluates to the given input.
in first example why did he used A-->epsilon instead of A-->0A...isnt that the leftmost derivation??
left most derivation means that we have to take left most variable and change it, not take the left most value of the left most variable in the derivation. Hope it helps!
@@technicalharshit2516 s->BS
s->2S
s->2A (A->epsilon)
S->2
WHYYYY THIS IS NOT POSSIBLE??????
@@anushkagarhawal6918 to find a corresponding PDA, for a given grammar we must have to consider all possible cases.
In other words, all possible strings obtained by productions rules must be accepted by PDA.
So to obtain each possible combination of strings that must be accepted, we are first using those production which involves more no. Of non-terminals symbols and then using production that involves terminal symbols.
Hope, you got that...!
@Mohd Sharique Alam, please refer to my comment above.
Then coming to your question, as you have seen in that video, that whenever we have a terminal symbol in the top-most stack we just advance the Input symbol, till a non-terminal symbol.
Since 'A' can have two productions, either string "0A" or ''epsilon". Now consider the case A->0A, so A is replaced by 0A in the top-most stack. Now we have '0' in the top-most stack which is a terminal symbol, so we will advance the string and (0, epsilon-->epsilon), and now the top-most symbol is again ''A", so using this production rule( A->0A ), we didn't get anything fruitful even we have make this PDA construction more complex.
I hope, I got there...!
@Vasu Sharma it all depends upon the grammer here just he took an example so according to that example he explained
Sir, Why had you used production A->€ instead of A->0A ?
Please explain it.
I dont understand that part either, answer would be good!
Because that production gives you two options, A->€ and A->0A. In that example, he wanted to look the most left derivation for the string 221. If you want to get the most left derivation for the string 2210, in that step you have to choose that option (A->0A) and then transform the non-terminal A to €.
I didn't understand either.. did you understand?
@@Menthosful ?
@@Menthosful ??? why did he take 221 and not any other possible string and if choosing only leftmost then shouldn't the string be 2210
Hi, I have a question I really urgently (like within a few a hours!) need an answer to: can you please explain why at 5:48 it doesn't become 2210A, then 2210? Am I missing something? I know some other people also wanted to know this answer. Thanks
bcoz it has taken production A-> ε over there.
Because the desired string is 221 we don't want anything else.
replacing A with epsilon
Is this question really answered with the below responses? I still don't see why it was 221 and not 2210A then 2210
I think it's upto us to take any one production from the 2 given (as was done in earlier examples too). So here he took A->€, rather than A->0A here.
got it, now ill be able to construct PDA for any CFG
❤❤
kya job lagti hai isse?
@@parthsarthisingh4549 hai ek job bhai jo isse lagti hai
I m having a doubt, what if our production going like this
A --> Aa | Yb
When PDA find non terminal A on top of stack then it would always took Aa not Yb.
How we can solve it ?
19:14, the 0102 on input matches the 0102 on stack, but what would happen if 0103 is on input and 0102 is on stack? Seems this branch of logic is not explained... any help?
Hey did you find out what to do in that case
Same question popped up in my head so I'm looking through comments but can't find any answer
All the different rules are different examples he has taken to show the working of the method, I got confused if they were relating to the grammar in the start of the video
Don't panic to see the comments that some students can't understand it , actually this topic is little bit complex, so you have to see the video twice or thrice for proper understanding 👍
Thank you sooo much sir your lecturer is very impressive i understood very clearly.........
Could you please explain to me ?
qassam kha ?
@@ansabrehman2208 😂😂😂😂literally
chal jhutti
This video was confusing, hard to track what is going on when
Good explanation. Thank you
is the general form mentioned in the video same for all such conversion problems?
could someone answer this question I have the same doubt
How did you get that general form??
It was not an exact general form. It is an example representative of the general form (not some special case)
Thankyou sir
kaihna kaya chatae ho aap ;-/
heavy yaar xD
you took one example and didn't continue with that
Sir the example we had was different and you solved the different one 😅
Sir, where did we get A-->BCD rule from? It's not present in the grammer.
Hi, will this general form for all grammars we will try to find equivalent pda?
Thank you so much sir really helpful lectures u r delivering.
U didn't continue with the starting examplee
Great video
what if input symbol and the top element on stack does not match?
will the result of left most derivation not be 2210 ?
What are you explaining. Just jumping from one example to another. Atleast complete an example. Did you had cheap weed
😭😭😂😂
Lmao
lol
If I have more than one rule with the same start variable what rule should be applied ?
kuch samjh ni aya 🥺🥺
bhai ye general form kaha se aaya?
Is there more than one PDA corresponding to the same CFG. For example, in lecture 81, You give an PDA for strings 0^n1^n, we know the CFG for these strings is X->0X1. If we use this CFG to derive the PDA, it is different from the one in lecture 81. How can we prove that these two PDA are the same? Or how can we simplify the derived PDA to the one introduced in lecture 81?
Sir please upload remaining videos soon, thanks
Thanks sir❤
21:55 for which context free grammar?
Is this topic important for gate purpose??
Yesss
Is the given rule same for all questions ?? plz reply thanks
SO good
Super teaching sir.
How you make the videos? By this viewers can capture more. Sir, during this lockdown we have to deliver lecture.
Thanks a lot
Do number of states matter in pda?
amazing video but you just left the first example you did. You broke it down but did not convert it
Damm bro 😎 if you are master in data structure or in Stack you can do it easily...
Zindagi chune engineering nahi.
PLEASE RESPOND.
How long do you need to finish the playlist?
Please finish in a month or two. Will be very helpful for our upcoming exams.
How much will you pay? A beggar with a choice lool
I don't understand why epsilon, epsilon -> S, should it be "epsilon, S -> A"?
same thing i thought
@@itxbo I think mine is correct! Trust me! I got a 14/20 on this course finally! XD
at least give an example
why you are not writing B as 2
s->BS
s->2S
s->2A (A->E)
S->2
??????
He said you can get many forms... So yours is not wrong too
My friend said you should use a better font
Got it 👍
What is the meaning of advance the input string ??
read the next symbol
Bit confusing
Sir a also gives oa A ->OA
Have you got your answer?
Yup, so 221 isn't the general form. You can have many forms accepted by the PDA.
First video with damm bad explanations.
Why can't it be like:
--> S
--> A
--> 0A
--> 0 .
Transition of PDA ?
Can u tell me?
purane lecture dekh le.
How can you get Left most derivation sir i mean without using inPut string?
Sir,please explain only by taking one grammar
the grammar and final PDA do not match
Little bit confusing
this is worst , u have not explained the example
So, So complicated. hard to understanding
pleasa add NPDA with this lecture set....urgent.....
I'm here cause Ganesh doesn't make any sense.
don't you just love paying for a class where you have to teach yourself all the material? :) this midterm's gonna suuuuuuuck
@@DamnLyons Hey, I'm shooting for at least 65% That's about all you can hope for in this class.
We can not see picture clarity
net sahi krwa bharrwe
ama kya padha rhe ho bhai...kuch smjhao to
Wahi to...read to hm b kr skte...
Sir,Is this enough for gate 2019?
not enough for more click mushermusicvevo where i explain
Not required for gate actually these type of one's
Very bad do one example only
Heyy
@@jj050 whi
@@jj050 waited...but u didn't come
@@jj050 tu soch
@@jj050 they are personal
@@jj050 yar meko pta hota to yhan kyun krti