[Cbc] preprocessing problem
John J Forrest
jjforre at us.ibm.com
Thu Apr 17 11:28:07 EDT 2008
Tuomo,
I have found one or two bugs in preprocessing recently. I intend to update
Cbc soon - I am just giving people a chance to get a reasonably stable
version.
If you send me problem I can see if latest changes will fix - or debug
problem.
John Forrest
From: Tuomo Takkula <tuomo.takkula at inform-ac.com>
To: cbc at list.coin-or.org
Date: 04/17/2008 10:09 AM
Subject: [Cbc] preprocessing problem
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
Telefon: +49-2408-14589-17, Fax: +49-2408-9456-45
tuomo.takkula at inform-ac.com, www.inform-ac.com
Registered AmtsG Aachen HRB1144 Gfhr. Adrian Weiler
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