13. Incremental Improvement: Max Flow, Min Cut 

Cut -> 46:45 Residual Graph -> 1:08:10 Augmenting Path -> 1:18:10

Wish I could sit in that room, answer your questions, get a frisbee :-) but it's still good. Thank you MIT for providing this level of education for free. If I grew up to earn sufficient money, I will surely donate so that you continue with this good work forever.

I don't know how I would survive algorithm classes in my school without these MIT lectures.

Only video about network flow I was able to understand - thanks MIT.

You're rocking it, Srinivas 🎉

The lecture is phenomenal!! Thank you very much MIT for making this course open-source to the public !!

Thank you very much! This was the first clear explanation of this topic. I highly recommend it to those who are studying "advanced algorithms" on coursera.

Very straightforward and clear explanation and illustrative examples. It made me understand this interesting subject! You did in an hour and 20 minutes what my teacher didn't in 2 hours!

if anyone's want to jump directly on finding cuts, @ 1:07:00 he starts to explain how you find min-cut

The Frisbee of true Computer Science!

fuck have an exam next week with this topic. The professor only gave us a week to understand the material. Of course doable for smarties and exceptions but as a normal person. So intimidating.

Love his enthusiasm!

How does the sum at 28:40 even work? The sum of flow values outgoing from all vertices except source and sink equals zero?

Honestly, the camera guys need to pay attention to the lecture. When he asks about something that's on the board, don't point the camera at Srini. Point it at the BLACKBOARD, so that the viewer can also try to answer the question.

A huge thanks and kudos to Professor Devadas.

The lecture is really good but the movement of the camera is making me dizzy.

Thanks MIT for these great lectures!

at 51:36, doesn't it break flow conservation since one of the nodes has 2 going in but 3 goes out?

at 56:14 , one student asked a question about why don't we consider path s -> c. Sirinivas said when you don't have a particular edge from s to c, you can use skew symmetry to argue s->c and c->s cancelled out each other. I don't get his answer. We are considering f(S, T), why does c->s get involved and cancel s -> c?

I have a doubt in the flow conservation formula. f(u,v) is 0 only for all edges between u and v right. If there's an indirect edge then we take it also as 0 right. In the case how f(s,t) also should be equal to 0 right as there's no direct edge between s and t?

a super short proof of the Theorem at 40:49: 0=f(V,V)=f(s,V)+f(t,V)+f(V-s-t,V) ({s}, {t}, V-s-t are disjoint sets). Since f(V-s-t,V) = 0 (by conservation property), f(s,V)+f(t,V)=0. i.e. f(s,V) = -f(t,V) = f(V,t)

He actually threw frisbee at students at an MIT lecture. That's hilarious....

Please, show me upper graph when you explain residual graph network flow, I didn't know that how it works.

Thank you very much.

That's a very nice explanation !

Perfect, thanks !

What was the point of disallowing self edges and cycles (u,v), (v,u) at 22:58? I'm not really sure I understand the difference between net-flow and positive-flow and the impact of the professor's assumption on the following definitions/constraints and therefore proof.

Informative!! I am eating information like never before :)

This is great. Thank you

Great Lecture! Wonderful!

Excellent explanation.

Amazing class!

What did that student mean at ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-VYZGlgzr_As.html?? We did consider c at f(d,c) which is -1 . Not sure what did he mean with his question.

How does f(u, v) work in skew symmetry when (u,v) are not connected by an edge?

The proof at 1:03:00 seems a bit odd. he has broken up the RHS term in the parenthesis into 2 parts( but the rules he gave earlier break the LHS term in the parenthesis )

Cut 47:00

is it related to gomory hu's algorithm?

How would you claim that using bottleneck value as the flow will always be correct ?

1:12:48 esidual network base on flow

Mr. Cameraman focus on the BOARD more than on the teacher.

Cool class

Can somebody Plz provide me the link to the next lecture, which is continuation of this one.. !!

at 42:14 why f(s,V)=f(V,V)-f(V-s,V)?

His bag is actually a 4-dimensional container

I saw Erik on the seat when camera zoom out

I think there is a small mistake at the end in the example. Edge from c-> t should be 0:2

my teachers never gave me frisbees

Min-cut example part not clear.

At the time point ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-VYZGlgzr_As.htmlm40s we can see some numeric summation and the graph diagram at once. That is helpful. Then after that we rarely see them both at the same time, which is not helpful. MIT does provide the pdf at their website for more clarity. Their is a unfortunate combination of red chalk, handwriting, and excess camera movement. There is a simple summation of values, positive and negative and the explanation does not reflect that simplicity. Looking at the pdf document and the video simultaneously is useful. MIT might consider full screen pip (picture in picture) and chalkboard centric view simultaneously for ease of viewing.

46:46 cut

What's CLRS?

its unbelievable he managed to extend a simple 20 minute topic (at max ) and lecture it for 1 hour and 22 minutes. im in 1h15min and still havent seen a defn about ford fulkerson method which he tries to explain. completely trash. if you want to learn the algorithm, dont waste your time on this video, watch ucdavis, idk.

I don't know about others but I don't like these kind of teachers