Thank you, your vid helps a lot! I just wish to ask one question. If by any chance you use LINGO, how do you code the first alternative to the software?
@jasminatf
2 жыл бұрын
Specifically for the constraint's repetition for each subtour and to calculate its cardinality. Is there any way to use sets in LINGO or do I have to explicitly type in all the subtour?
@lckung.lectures
2 жыл бұрын
@@jasminatf Thank you for asking! However, I'm sorry that I never had a chance to use LINGO in my life, so I have no answer for that. Hope that you will find an answer soon!
@jasminatf
2 жыл бұрын
@@lckung.lectures okay, thanks😊
@nhuphuongnguyen551
2 жыл бұрын
thank you sir
@lckung.lectures
2 жыл бұрын
Thank you!
@EmilioGarcia_
2 жыл бұрын
Prof. thank you for the video, great content! I have a naive question, discribing the exact numbers of constraint for alternative 1, I don´t get what are the 2 ways to choose a subset of zero node or n nodes, could you please elaborate on this? Thank you.
@lckung.lectures
Жыл бұрын
I guess you are talking about that "minus 2"? When we have n elements, we have 2^n ways to select "some" of them. In the 2^n ways, one is to select all of them, and another one is to select none of them. We omit these two choices when we write down the constraint.
@sohambhowal3510
Жыл бұрын
Hi prof, thanks a lot for explaining in so much detail. But I've a doubt with the subtours 1st method, suppose we take a subset of 4 nodes, then there can still be a cycle of 3 edges among 3 nodes. And that will satisfy the cardinality - 1 condition. So is there an error with that subtour?
@lckung.lectures
Жыл бұрын
But for that three nodes, they also form a subset, and there is a constraint for that subset to contain at most two edges. That subtour then cannot exist.
@lijiali-nl7ip
Жыл бұрын
hello prof,thanks for your teaching,but i have a question with 1st method,does V include all nodes or V represent the customer node(without the depot node). if V include the depot node ,it seems that the method 1 doesn't work:)
@lckung.lectures
5 ай бұрын
I think V includes all nodes, and I tend to believe that method 1 works. If you see a reason for method 1 to fail, it would be great if you may share with us!
@wangruochen6754
2 жыл бұрын
Hello. I just have a small question. At 1:35, why SET S cannot be SET V?
@lckung.lectures
2 жыл бұрын
For the set of all nodes, V, if we also impose that constraint, we will say "a tour can have at most n - 1 edges". But a feasible tour must have n edges, so allowing S to be V will make the whole formulation having no feasible solution.
@vinitrancoso
Жыл бұрын
how can I write the first alternative in Cplex code ?
@lckung.lectures
Жыл бұрын
I would first create a set to contain all those subsets and then use that set to do the first way. Maybe you may also try it!
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