[Cgl] knapsackcover seems to cut off optimal solution

[Robin Lougee-Heimer]

Ashutosh: 

If this is still an issue, will you please report it in the Cgl bug 
tracking factility? 

https://projects.coin-or.org/Cgl/report

thanks,
Robin

----------------------------------------------------------------------------------
Robin Lougee-Heimer, PhD
Program Manager, COIN-OR
IBM TJ Watson Research Center
1101 Kitchawan Road, Yorktown Heights, NY 10598
ph: 914-945-3032   fax: 914-945-3434 
robinlh at us.ibm.com
http://www.coin-or.org





Ashutosh Mahajan <asm4 at lehigh.edu> 
Sent by: cgl-bounces at list.coin-or.org
10/26/2009 03:18 PM

To
cgl at list.coin-or.org
cc

Subject
[Cgl] knapsackcover seems to cut off optimal solution






one of the users of symphony provided an instance on which the 
KnapsackCover
cuts off the optimal solution.

the LP files and the code that reproduces the problem are located here:

http://coral.ie.lehigh.edu/~asm4/tmp/knapsack/

out1.lp is the original instance. out2.lp is the instance obtained after
adding CglKnapsackCover inequalities. solving out2.lp with cplex or cbc 
gives
a solution value of 401, while out1.lp gives 397.

This behaviour was seen with latest stable r792. i expect it in the 
release
version as well (though i did not check). is this a bug, or something 
wrong
with my construction?

thanks.
--
regards
Ashutosh Mahajan
http://coral.ie.lehigh.edu/~asm4

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