GAMS World Forum

Hi, I am working on a min. problem with Conic Scalarization. In the subproblems of the model (NLP), it stucks on 0.10% (while: w1=1, w2=1, alpha=0.9, means that 9th iteration). It is not giving with a best integer solution. Is there a way of jumping of it. I get txt output file in each loop. Maybe, ...

You have implemented a semicont variable (https://www.gams.com/44/docs/UG_LanguageFeatures.html#UG_LanguageFeatures_Semi-ContinuousVariables). Many solvers do support them natively. But performance is usually comparable to your own binary reformulation (if your bigM is small enough). -Michael Hello...

I have just solved, but still wondering if any more sophisticated solution. I have just added three constraints with a new binary variable; It makes holdtime either 0 or greater than 50 secs. c11(i,w1,w2)$(ord(w1)<>ord(w2)).. holdtime(i,w1,w2) =g= 0 - m*y(i,w1,w2); c12(i,w1,w2)$(ord(w1)<>ord(w2)).. ...

Hi all, I want to use a lower boundary for a positive variable (holdtime(i,w1,w2)) iff the flight (i) requires it. If I use holdtime.lo(i,w1,w2)>=50, the model gives 50 secs to all flights(i). But, I just want iff the flight requires holdtime going from w1 to w2., then it can get at least 50 secs. t...

Hello, How can I iterate the txt file name (trial-1, trial-2, ... etc.) to get variable values for each weight set (w1, w2) in multi objective opt. model? OR, is it possible to get these in an excel file with different sheets? For example; the results of weight set (5,2) will be exported to the shee...

I couldn't be familiar in your code, but, as I know, if you want to use a set indices in the $ condition, you should use with "ord". For example; sum(i$(ord(AMinus) > 5), x(i,j)) .....etc Because you defined "AMinus" as a set. (but, still, I am not quite sure this is what you mea...

Hello Michael, I checked it out! However, I am very far away to implement any of them. I am not familiar those. I tried to follow the lines but I am lost. But, I guess the mcfilter solves a problem, then save it and then runs the pareto.py then saving the results. But, I couldn't do it. I have gdx f...

Hello everyone, I have a multi objective optimization problem with 3 objectives. I applied Conic Scalarization since I am not quite sure whether it is convex or not. Anyway, in the end, I have a Excel sheet that have weights, alphas and z1, z2 and z3 scores of Conic Scalarization. But, the problem i...