Eli Towle

Hi Hanxiong, You have to write the model in a form that Gurobi can solve. You won't be able to define your own black-box function and add it to a constraint. If your constraint isn't in a form supp...

Hi Hooman, In general, it's okay to set a continuous expression equal to an integer-valued expression. This would just force the continuous expression to take on an integer value at a feasible solu...

Hi Mohammad, Yes, optimizing a model in two steps like this can affect the solution returned by Gurobi. With the first approach, Gurobi performs a single solve with a time limit of one hour and opt...

Hi Hooman, You can try to compute an irreducible inconsistent subsystem with Model.computeIIS(). This is a subsystem of constraints/bounds that together is infeasible, but is feasible if any one of...

Hi Hooman, It looks like the parentheses on \( \texttt{constraint4} \) are not placed correctly. The \( \texttt{for} \) loop should be inside of the \( \texttt{sum} \) function. You can write this ...

Hi Regina, By default, variables added using Model.addVars() are nonnegative. Perhaps this is the problem, since the solution to the system \( Hq = 0 \) is restricted to the set \( \{ q \colon q \g...

Hi Erik, You create the \( \texttt{x[i, j, t]} \) variables under the condition that \( \texttt{i != j} \): if i != j: # AGV arcs between cluster nodes x[i, j, t] = m.addVar(vtype=GRB.BINARY,...

Hi Xin, Sure, I try to answer questions here when I have some spare time. Eli

Hi, Model.addVars() adds new variables to the model, just like Model.addVar(). Because you don't supply a name to these variables, the default names \( \texttt{C0} \), \( \texttt{C1} \) , etc. are ...

Hi Hooman, Sorry, it is still not clear to me exactly how to reproduce the error. The code you posted does not run by itself, since there is spacing in Python variable names, trailing colons at the...