[Cbc] preprocessing problem

[Tuomo Takkula]

Hi,

on a mps file vanilla cbc reports

   Cgl0000I Cut generators found to be infeasible!
   Pre-processing says infeasible or unbounded

If I switch off preprocessing (preprocess off in cbc shell), then the
problems solves just fine. Is there a bug in preprocessing rendering a
feasible problem into an infeasible? Is there a simple way to get more
output from preprocessing (log and slog do not help).

The preprocess options I tried are the following:

off             solves
on              infeasible
equal           infeasible
sos             infeasible
trysos          infeasible
equalall        infeasible
strategy        solves after some complaints:
                 Cgl0000I Cut generators found to be infeasible!
                 Cbc0006I The LP relaxation is infeasible or too expensive
aggregate       infeasible


The mps file is available from me on request - write to
tuomo.takkula at inform-ac.com.


Best regards
Tuomo Takkula



-- 
__
Dr. Tuomo Takkula
Geschäftsbereich Systeme Logistik
INFORM GmbH,     Pascalstraße 23,    52076 Aachen
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