[Coin-discuss] integer column bounds fixed by CBC/CLP?

[Kish Shen]

On Sunday 25 June 2006 11:36, John J Forrest wrote:
> This was deliberate so that further processing could be done.  Even if you
> reset bounds then some information has been modified e.g. best solution.
> Suggested way of doing repeated runs is as in Cbc/examples/repeat.cpp and
> also see references to referenceSolver in CbcModel.hpp
>
> John Forrest
>
>
John, thanks for your quick reply!

I have updated my code so that it saves a reference solver just before doing 
the MIP, and then after the solve, extract the required solution information 
(variable solution values, reduced costs, etc.), and then reset to the 
reference solver. 

Am I correct in that the MIP can add extra rows to the problem by posting more 
cuts to the problem? Also, can the presolve remove columns/rows from the 
problem? Are these changes visible in the model after the solving? CPLEX and 
XPRESS allows the user to extra information from the probelm using the 
original rows/column numbers, and this is important for our usage, as they 
map to the user's variables and constraints. 

Cheers,

Kish Shen