Hello,

I am running into an issue when attempting to impose a constraint within my model. The constraint that I want to impose is that all values for a variable in a set are >=0. Unfortunately, when I solve the model, I get results that do not account for this constraint (i.e., many values for the variable are negative). As you can see in the output below, AMPL/knitro is stating that there is no constraints in my model.

I have set my constraint up as follows:

subject to effort_constraint {(t,o) in CHOICE_SETS}: effort[t,o] >=0;

where I have the following sets, variables, and data (for reserve):

set TIMES;

set OPTIONS;

set CHOICE_SETS within TIMES cross OPTIONS;

var a0 >= -3, <= 3 default .1;

var a_reserve >= -3, <= 3 default .1;

var effort {(t,o) in CHOICE_SETS} = a0 + a_reserve * reserve[t,o] ;

Below is the output from AMPL.

Substitution eliminates 1822104 variables.

Adjusted problem:

87 variables, all nonlinear

0 constraints

1 nonlinear objective; 87 nonzeros.

#presolve 0.016568 16777224 3103628912

#output 1.50372 0 3103628912

Artelys Knitro 12.4.0: outlev=6

par_numthreads=24