# Tag Info

6

Integer programming models solved by CPLEX (or most other solvers) require linear or, in certain very limited cases, quadratic constraints. Your constraint 9 involves dividing a parameter (h) by an integer variable (man), which results in a nonlinear expression. Multiplying both sides by man will not help, since that produces an equation with products of ...

6

There are many useful references that can be found by googling. In the following you can find some of them: IBM ILOG CPLEX Optimization Studio OPL Language User’s Manual Introduction to Computational Optimization Models for Production Planning in a Supply Chain A Deep Dive into Strategic Network Design PS: About the first mentioned reference, it is about (...

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your model is not feasible and that is why you get no solution. if you comment //forall(i in cD,j in DI,t in T:t==2, f in F)cb10:recievetime[i][t]+(time[i][j]+servicetime[j][t])*K[i][j][f]-Tmax*(1-K[i][j][f])<=recievetime[j][t]; then you ll get some conflicts and relaxations like 72 [0,Infinity] [-6,Infinity] delta 72 [0,Infinity] [-10,...

4

as can be read in OPL CPLEX documentation, A decision variable is an unknown in an optimization problem. For instance dvar int x in 0..10; is a decision variable int a=3; is some data definition whereas in execute { var b=2; } b is a scripting variable. In your model, I see float Q[periods]; //Inventory of the blood product at the blood center in time ...

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There is a rather helpful list of educational resources specific to IBM Decision Optimization products here. If you scroll down a bit, you will find links to some YouTube videos about optimization modeling using OPL (and the CPLEX Studio IDE).

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I recommand the Model Building Book by Williams and here you may see the examples in OPL. Let me add some OPL links: How to with OPL ? Tips and tricks OPL Scripting OPL and Excel Making Optimization Simple

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Here is a book that Pete Cacioppi wrote to teach OPL and optimization as it relates to network design models. It was meant for beginners. It uses a network design problem as the example, but you don't need to get the Supply Chain Network Design book to use this one.

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if you name other constraints as: forall(i in cD, t in T:t==2) cb1:sum(j in DI)K[i][j]<=1; forall(i in cD,j in DI,t in T:t==2) cb2:e[i][j]*K[i][j]-(1-K[i][j])*Q <=y[i][t]-y[j][t]; forall(i in cD,j in DI,t in T:t==2) cb3:y[i][t]-y[j][t]<=e[i][j]*K[i][j]+(1-K[i][j])*Q; forall(i in cD,j in chargestationcopy,t in T:t==2) cb4:e[i][j]*K[i][j]-(1-K[i][j])...

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in the sched_sequence example in OPL CPLEX you have an example of array of sequences: dvar sequence workers[w in WorkerNames] in all(h in Houses, t in TaskNames: Worker[t]==w) itvs[h][t] that should help you regards

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