Pyomo + Couenne: Infeasibility results in Exception?

[sascha...@gmail.com]

Hi,

i'm trying to use Pyomo + Couenne to solve MINLP-problems.

After implementing my constraints, ready to debug, the following behaviour surprised me:

Code:

self.opt = SolverFactory('couenne')

self.m = ConcreteModel()

...

...

print('Solve')

self.opt.solve(self.m)

print('Finished solving')

(Check result state here...)

But the program never reaches the second print, because the following exception is happening:

Solve

Traceback (most recent call last):

  File "X.py", line 601, in <module>

    result = opt.solve_model()

  File "X.py", line 494, in solve_model

    self.opt.solve(self.m)

  File "C:\Miniconda3_64\lib\site-packages\pyomo\opt\base\solvers.py", line 578, in solve

    result = self._postsolve()

  File "C:\Miniconda3_64\lib\site-packages\pyomo\solvers\plugins\solvers\ASL.py", line 202, in _postsolve

    return SystemCallSolver._postsolve(self)

  File "C:\Miniconda3_64\lib\site-packages\pyomo\opt\solver\shellcmd.py", line 161, in _postsolve

    results = self.process_output(self._rc)

  File "C:\Miniconda3_64\lib\site-packages\pyomo\opt\solver\shellcmd.py", line 239, in process_output

    suffixes=self._suffixes)

  File "C:\Miniconda3_64\lib\site-packages\pyomo\opt\plugins\sol.py", line 79, in __call__

    raise ValueError(msg)

ValueError: Error reading "C:\Users\X\AppData\Local\Temp\tmpdewalm5n.pyomo.sol": no Options line found.

SOL File Output:

 Couenne (C:\Users\X\AppData\Local\Temp\tmpdewalm5n.pyomo.nl May 18 2015): Infeasible

Options

3

0

1

0

238

0

86

0

objno 0 220

What is happening? Pyomo should not raise an exception just because the problem is infeasible, right? My code neaver reaches the part where these result-states may be checked!

My environment:

Pyomo (4.2.10784)

pyomo.extras (2.0)

Python 3.4.3 (64-bit) @ Win7

Thanks!

Sascha

[Gabriel Hackebeil]

Would you mind sending me a copy a sol file the causes that error? Our SOL file parser might just need a little tweaking.

Gabe

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[Gabriel Hackebeil]

Sascha,

Thanks for sending me the solver files. The SOL file that you sent had some subtle whitespace differences on the first line that caused our SOL file parser to fail. I’ve fixed the issue on Pyomo trunk. If you can’t install trunk then you can try manually adding line 52 and 53 from this file: https://software.sandia.gov/trac/pyomo/browser/pyomo/trunk/pyomo/opt/plugins/sol.py?rev=10903.

Gabe