[Coin-discuss] osiclpsolver optimal for infeasible problem?

[Jan-Willem Goossens]

Hi all,

I tried to enter the following simple problem through the
OsiClpSolverInterface:

min  x1 - x2
s.t. x1 == -1

x1 >= 0, x2 >= 0

This problem is primal infeasible and also dual infeasible.
I enter it as follows


	OsiClpSolverInterface *s = new OsiClpSolverInterface();

	double inf = s->getInfinity();
	CoinPackedVector empty;

	s->addCol(empty, 0.0, inf, 1.0);
	s->addCol(empty, 0.0, inf,  -1.0);

	CoinPackedVector r0;
	r0.insert(0, 1);
	s->addRow(r0, -1.0, -1.0);

	s->setObjSense(1);

	s->initialSolve();

So the "x1 == -1" is entered as -1 <= x1 <= -1.

The output is as follows:

Coin0508I Presolve thinks problem is unbounded
Clp3003W Analysis indicates model infeasible or unbounded
Clp0006I 0  Obj 0 Primal inf 1 (1) Dual inf 1 (1)
Clp0006I 0  Obj 0 Primal inf 1 (1) Dual inf 1 (1)
Clp0006I 0  Obj 0 Primal inf 1 (1) Dual inf 1 (1)
Clp0006I 0  Obj 0 Primal inf 1 (1) Dual inf 1 (1)
Clp0006I 0  Obj 0 Primal inf 1 (1) Dual inf 1 (1)
Clp0006I 0  Obj 0 Primal inf 1 (1) Dual inf 1 (1)
Clp0006I 0  Obj 0 Primal inf 1 (1) Dual inf 1 (1)
Clp0006I 0  Obj 0 Primal inf 1 (1) Dual inf 1 (1)
Clp0006I 0  Obj 0 Primal inf 1 (1) Dual inf 1 (1)
Clp0006I 0  Obj 0 Primal inf 1 (1) Dual inf 1 (1)
Clp0006I 0  Obj 0 Primal inf 1 (1) Dual inf 1 (1)
Clp0006I 0  Obj 0 Primal inf 1 (1) Dual inf 1 (1)
Clp0032I Optimal objective 0 - 0 iterations time 0.052

The s->getColSolution() shows x1 = x2 = 0.0, and of all the "s->is...()"
functions, only s->isProvenOptimal() returns true.


Not unimportantly, I'm running this using Visual Studio .NET 2003, so
there might be something there.
I'm wondering if others get the same results?
Or am I missing something?

Regards,

Jan-Willem Goossens