# (binary) solution not satisfying constraint
**URL:** https://discourse.julialang.org/t/binary-solution-not-satisfying-constraint/30998
**Category:** Optimization (Mathematical)
**Created:** [November 12, 2019, 9:58am UTC](https://discourse.julialang.org/t/binary-solution-not-satisfying-constraint/30998 "2019-11-12T09:58:15Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@mposs](https://discourse.julialang.org/u/mposs)
#### Post date: [November 12, 2019, 9:58am UTC](https://discourse.julialang.org/t/binary-solution-not-satisfying-constraint/30998/1 "2019-11-12T09:58:15Z")
Hello
I’m solving a small problem with Gurobi, which is given by `println(cover)`=
```julia
Min slack[1] + slack[2] + slack[7] + slack[9]
Subject to
y[135] + y[136] + y[152] + y[158] + y[159] + y[200] + y[474] + y[550] + y[551] = 2.0
y[135] + y[136] + y[152] + y[158] + y[159] + y[200] + y[474] + y[550] + y[551] + slack[1] ≥ 1.0
y[135] + y[136] + y[158] + y[474] + y[550] + y[551] + slack[2] ≥ 1.0
y[135] + y[136] + y[152] + y[158] + y[159] + y[200] + slack[7] ≥ 1.0
y[135] + y[136] + y[152] + y[200] + y[474] + slack[9] ≥ 1.0
slack[1] ≥ 0.0
slack[2] ≥ 0.0
slack[7] ≥ 0.0
slack[9] ≥ 0.0
y[135] binary
y[136] binary
y[152] binary
y[158] binary
y[159] binary
y[200] binary
y[474] binary
y[550] binary
y[551] binary
```
The returned solution is `println(value.(y))`=
```julia
1-dimensional DenseAxisArray{Float64,1,...} with index sets:
Dimension 1, Any[134, 146, 158, 550, 551]
And data, a 5-element Array{Float64,1}:
0.0
0.0
0.0
0.0
1.0
```
which does not satisfy the first constraint. How is that possible? (I can unfortunately not easily share the code).
Best,
Michael.
---
### Author:  [@blegat](https://discourse.julialang.org/u/blegat)
#### Post date: [November 12, 2019, 12:00pm UTC](https://discourse.julialang.org/t/binary-solution-not-satisfying-constraint/30998/2 "2019-11-12T12:00:56Z")
What are the values of `raw_status(model)`, `termination_status(model)` and `primal_status(model)`?
---
### Author:  [@mposs](https://discourse.julialang.org/u/mposs)
#### Post date: [November 12, 2019, 3:30pm UTC](https://discourse.julialang.org/t/binary-solution-not-satisfying-constraint/30998/3 "2019-11-12T15:30:42Z")
```julia
raw_status(model): Model was solved to optimality (subject to tolerances), and an optimal solution is available.
termination_status(model): OPTIMAL
primal_status(model): FEASIBLE_POINT
```
By the way, the solution has been found heuristically, as can be seen in the output:
```julia
Optimize a model with 5 rows, 9 columns and 20 nonzeros
Variable types: 4 continuous, 5 integer (5 binary)
Coefficient statistics:
Matrix range [1e+00, 1e+00]
Objective range [1e+00, 1e+00]
Bounds range [0e+00, 0e+00]
RHS range [1e+00, 2e+00]
Found heuristic solution: objective 0.0000000
Explored 0 nodes (0 simplex iterations) in 0.00 seconds
Thread count was 1 (of 8 available processors)
Solution count 1: 0
Optimal solution found (tolerance 1.00e-04)
Best objective 0.000000000000e+00, best bound 0.000000000000e+00, gap 0.0000%
```
---
### Author:  [@odow](https://discourse.julialang.org/u/odow)
#### Post date: [November 12, 2019, 3:35pm UTC](https://discourse.julialang.org/t/binary-solution-not-satisfying-constraint/30998/4 "2019-11-12T15:35:47Z")
Without code, it’s hard to offer advice.
It looks like there is a bug in your code because the printed values have 5 elements, but it looks like your model has many more. Moreover, y[134] appears in the solution, but not in the model.
---
### Author:  [@mposs](https://discourse.julialang.org/u/mposs)
#### Post date: [November 12, 2019, 3:45pm UTC](https://discourse.julialang.org/t/binary-solution-not-satisfying-constraint/30998/5 "2019-11-12T15:45:58Z")
Oops, indeed, I pasted the wrong model. Here comes the correct one:
```julia
Min slack[1] + slack[2] + slack[7] + slack[9]
Subject to
y[134] + y[146] + y[158] + y[550] + y[551] = 2.0
y[134] + y[146] + y[158] + y[551] + slack[1] ≥ 1.0
y[134] + y[551] + slack[2] ≥ 1.0
y[134] + y[146] + y[158] + slack[7] ≥ 1.0
y[134] + y[146] + slack[9] ≥ 1.0
slack[1] ≥ 0.0
slack[2] ≥ 0.0
slack[7] ≥ 0.0
slack[9] ≥ 0.0
y[134] binary
y[146] binary
y[158] binary
y[550] binary
y[551] binary
```
I’ll see if I can create a small instance of the bug.