Hi Alex,
Thanks for your help! We really appreciate your sharing in LinkedIn and GitHub. These posts do help a lot!!
The new problem is: Dual infeasible due to empty column 'q({2})({1})'.
I am working on a bi-level programming problem with the KKT condition actually. I guess the reason for error is because there are different number of paths available for different orders.
For instance, there are two orders and three paths. Order A could select one path from three alternatives (p1, p2 and p3), while Order B could select p2 or p3 only.
So decision variables are q[1][1], q[1][2], q[1][3], q[2][2] and q[2][3]. Then CPLEX can't get a feasible dual formulation.
Do you have any idea to express q[k][p]
more tight?
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Ying Qi
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Original Message:
Sent: Tue July 27, 2021 03:56 AM
From: ALEX FLEISCHER
Subject: index is a sub tuple
Hi,
in
you could have a look at array variable indexer size - 3 ways : union , tuple set, decision expression
and for your second question
{int} S={1,2,3}; tuple path { int i; {int} Sequence; } {path} paths={<1,{1}>,<3,{3}>}; int a[s in S][p in paths]=(s in p.Sequence); execute { writeln(a); }
gives
[[1 0] [0 0] [0 1]]
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[Alex] [Fleischer]
[EMEA CPLEX Optimization Technical Sales]
[IBM]
Original Message:
Sent: Mon July 26, 2021 02:41 AM
From: Ying Qi
Subject: index is a sub tuple
Hi all,
I am working on the multicommodity flow problem.
tuple Order{ key int no; string origin; string dest; int volume; } {Order} orders =...;tuple Path { key int id; int price; {int} sequence;}{Path} paths = ...;{Path} orders_paths[k in orders] = ...;
1. I want to define a int+ variable q[k in orders][p in orders_paths[k]]. Do you know how to define q? The size of orders_paths[k] is different.
2. I also want to get an matrix a[s in S][p in paths]. S is a set. if s belongs to p.sequence, then a[s][p] = 1, 0 otherwise. Do you know how to get this matrix automatically?
Many thanks.
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Ying Qi
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#DecisionOptimization