[Couenne] Binary Variables

[Murilo Souza]

Hello, i'm using Couenne in Atom/Juno, through Julia language, to solve some MINLP problems.

But i have an issue with this following problem (it's a random problem i just wrote to test the Couenne solver in Atom):

## Solve test problem
 #
 #  min   100 * (x5 - (0.5 + x4) ^ 2) ^ 2 + (1 - x4) ^ 2
 #  s.t.  x4*x3 + x5*x1 <= 20
 #        5*x1 - 2*x5 + 3*x3 <= 17
 #        x4, x5 binary
 #        0 <= x1 <= 3
 #        0 <= x2 <= 5
 #        0 <= x3 <= 10
 ##

The problem is being solved to optimal point, but my binary variable x4 is not assuming a binary value. Here is the solution i found:

x1 = 1
x2 = 2.5
x3 = 2
x4 = 0.50124...
x5 = 1

Why is this happening? How can i fix this?

Thanks in advance,
Murilo Souza
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