Operations Research 05B: Primal & Dual Problems

[@YongWang]

Hi Guys, please comment and let me know what you think about this Operations Research Open Course. Your feedback is really appreciated. If you enjoy the video, please subscribe and share. All my replies here are only related to the content in my own videos. I am afraid I won't be able to answer other questions. Thanks for your understanding.

[@ccuuttww]

This open course cover most of the topic in research operation I expected u can also go through more in metaheuristics quadratic programming u may think this kind of topic is out of the scope in research operation however as a machine learning selflearner we always try different appoarch for a single problem for example duaility and primal is a key idea in SVM

[@Calliope-em4ln]

This is the most efficient video about duality I have ever seen. The first three minute is indeed exciting, as this is the first time I understand why we can change a maximizing problem to a minimizing one. Thanks for your video!

[@ThomasEdwards-i8p]

These videos have been an absolute life saver - it takes a very complex topic from a very long textbook and makes it super accessible and easy to understand. Thanks very much for the effort in making these videos.

[@raideno56]

This was the best video i ever watched about Primal & Dual Problems, Thanks a lot sir.

[@hoyintam4029]

The best explanation i have ever seen for prim-dual problem!

[@YongWang]

Glad to hear that, HoYin. Thanks

[@joshwkl]

Thank you SO MUCH!!!!!! Really saved my life before the exam!!!!

[@YongWang]

thanks for the comment, zerong

[@entertainviavaishu589]

Hlo

[@aliceelvis8262]

It's very short and clear. easy to understand.

[@YongWang]

Glad you liked it, Zichuan

[@vaibhavsingh77]

Your Explanation is Amazingly Epic!

[@AmitYadav-zs4ft]

This is such a short and clear explanation. Thanks for sharing it.

[@degigerel6286]

2:39, where are these 0,10,-10,-0,-0 ... numbers coming from ? I understand we need to change the direction of sign by multiplying by a negative numbers. But why exactly 0,10,-10,-0,-0??? Please help me to understand this.... AAHAA !!! I HAVE JUST GOT IT... IT IS BECAUSE OF THE COEFFICIENTS 30X1 AND 100 X2 HAVE TO MATCH...

[@idilbayarr]

At the first time I did not understand it too, thank you for your explanation :)

[@meghabhasker374]

I still don't get it

[@mossfoobar8322]

This was an awesome tutorial mr. Wang

[@YongWang]

Thanks, mohsen

[@fourier9641]

Phenomenal explanation. Thank you for sharing.

[@degigerel6286]

gosh i am glad i found this. This quantitative methods course is killing me...

[@KhoaTran-sh1do]

What a clear explanation! Thank you.

[@yingnanhe90]

This is very helpful in showing an operation different from my textbook. Thx.

[@tymothylim6550]

Thank you very much for this video! I learnt quite a bit on this topic!

[@achillesarmstrong9639]

much better than the text book thank you

[@YongWang]

Thanks for the comment, Achilles. What textbook are you using by the way?

[@andrewtsui9754]

Thank you, I got a lot from this vedio.

[@adhoc3018]

Very nice and concise explanation, thank you

[@alirezatanoori]

Thank you so much! Now i can understand the dual problem

[@michalcertik249]

Greatly explained. Thank you.

[@YongWang]

You are welcome, Michal

[@Cucumber4413]

1:50 Why do you multiply the first constraint by 0?

[@mossfoobar8322]

We simply do not need it. We want to create something like objective function with the exact value of 30 and 100 as coefficients and you can choose any of the equations you want as long as when you add them up they will result in 30 for X1 and 100 for X2.

[@YongWang]

Rok, I think mohsen answered your question.

[@3shtrlb]

@@mossfoobar8322 hi, if this is so, why didn't we multiply -10 to constraint #4 (x1 >= 0) ? the resulting function would still be 30x1 + 100x2 but will be =< 400 ? thanks in advance

[@nikhilkunjir3322]

I couldn't understand what lower and upper bounds of optimal solution are..

[@crazybuzurg6258]

Thanks a lot! Simple and clear!

[@justinl2009]

Quick question: Is the transposition the same if the primal was a minimization problem? Would it use 'larger than equal to' instead?

[@איתמרברציון]

Thanks a whole bunch, very helpful video indeed.

[@sehajgaba6167]

Thank you Sir .... it's really very helpful

[@leotorres300]

Much easier applied method than all that fluff in Convex Optimization from Boyd.

[@aslaniefaisal6709]

This is great. Thank you Sir.

[@evenong501]

Dr Yong Wang, can I get the slide ppt for this? TQ.

[@danielc4267]

Concise. Thank you!

[@YongWang]

No problem, Daniel

[@hosseinfaridnasr2778]

Can you explain what happens if we have the dual problem in matrix form. I think that would be easier to understand and use.

[@tyronelagore1479]

It would have been way more effective if you would have explained why you were multiplying and adding the constraints together to find your bounds. You explain you were trying to find a bound then you instantly jump to modifying and adding constraints together. Instead of explaining why adding and multiplying constraints by coefficients will help you find a bound.

[@CRIMSONDRAGON56]

What?... I think I understand what he was trying to do there but at the same time it's still just not clicking in my head.

[@YongWang]

Probably because of my accent? :)

[@CRIMSONDRAGON56]

@@YongWang Hahaha maybe! But your English is still quite good. I ended up understanding it in the end so thanks!

[@hoomanseyfi1941]

well explained. thank you. your voice is so monotonous. raising and falling has been proven to raise consciousness

[@YongWang]

Thanks for the advice, Hooman. I'll improve on that.

[@hoomanseyfi1941]

Yong Wang you're welcome. Keep up good work. And Good luck

[@muhammadfareza3107]

why multiply by -10 why not multiply by -1 instead? so you dont change much of the constraints?

[@YongWang]

Muhammad, you are trying to match the objective function coefs. Try multiplying by -1 and see if you can get those coefs.

[@hannahcora5939]

this is good stuff thankyou

[@YongWang]

hope you like it, hannah

[@carolllj]

very clear thank you!!!

[@xuelinnickcui5432]

Very nice. Thanks.

[@Micheljanos1]

negative 0??? Should be -1

[@ChauhanClasses09]

good one

[@YongWang]

Hope you like it, royal

[@jbond5834]

very good

[@YongWang]

Thanks for the comment, James Bond.

[@jbond5834]

hahha

[@nicholascurtis7337]

Ur a magician

[@YongWang]

Thanks, Nicholas

[@entertainviavaishu589]

Min z=6a+7b+3c+5d Subject to:. 5a+6b-3c+4d≥12 1b+5c-6d≥10 2a+5b+1c+1d≥8 a,b,c,d≥0 Solve this question please

[@oussamaelhousni5665]

awesome :)

[@LuLu-js7ku]

why is the minimun upper bound exactly equal to the max z value,not the maximun one ?