[Coin-lpsolver] Presolve removed variable's values?

[Candas, Mehmet]

Hi, 

I think presolve has option, to keep the original variable and
constraint names. I haven't done this before, but I see this information
in CLP User Guide. 

Mehmet, 

-----Original Message-----
From: coin-lpsolver-bounces at list.coin-or.org
[mailto:coin-lpsolver-bounces at list.coin-or.org] On Behalf Of Sathi
Sent: Thursday, February 15, 2007 10:03 AM
To: coin-lpsolver at list.coin-or.org
Subject: [Coin-lpsolver] Presolve removed variable's values?

Hi,

I have an LP problem in which presolve removes a lot of variables. I
have
attached the presolve statistics for a model I have.

While solving the presolved model, I would like to use some
relationships
between the original variables in guiding the pivoting heuristic.  So I
am
interested in two issues:

1. Which variables are removed? How do the variables in the presolved
model map to the original variables?

2. What values are the removed variables fixed at, if any?  Or, are the
values of some of the removed variables are only fixed during
postsolving
process?

I am at present looking at presolve literature and also the COIN
presolve
codes to figure out these issues. Any help would be useful to me.

Thanks,
Sathi

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