Hello, 

example of my problemrange time=1..5​
dvar float+ BTRY[time]
dvar boolean Prd[tasks][time]
subject to:
forall(t in time) BTRY[t] == minl(GBTRY,maxl(0, BTRY[t-1]+Pow[t]-sum(m in tasks)PD[m]*PT[m]*Prd[m][t-1]))

In the constraint i used t-1, which is out of bounds of the array, how can I define BTRY[0], and Prd[m][0].
If i change the array or implement a range time2= 0..4 it always conflicts with BTRY[t].

I can use the modell with forall(t in time: (t-1) in time), but i am not able to control the value of BTRY[0]

Thanks in advance.

#DecisionOptimization

A typical trick for this is to define two ranges:
range time0 = 0..5;
range time = 1..5;
The range relevant for modeling is still time but in the definition of variables you use time0:
dvar float+ BTRY[time0];
dvar boolean Prd[tasks][time0];
Then you add constraints that fix the variables at time 0 to some value, for example 0.
BTRY[0] == 0;
forall (t in tasks) Prd[t][0] == 0;
Fixing the variables at time 0 to zero can also be done in the definition of the variables:
dvar float+ BTRY[t in time0] in 0..(t == 0 ? 0 : infinity);
dvar boolean Prd[i in tasks][t in time0] in 0..(t == 0 ? 0 : 1);

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Daniel Junglas
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