[Osi] milp support in OSI

Laszlo Ladanyi ladanyi at us.ibm.com
Thu Apr 23 10:55:43 EDT 2009

I think Osi should not even support solving MILPs... Even that 
branchAndBound() call should be taken out... It's an entirely 
different story that there could be another class that supports MILPs 
and is built on top of Osi. There is a plan (for x years now, x>3) to 
rewrite Osi with allowance for simplex based methods and MILP related 
methods all nicely separated into distinct classes, data handling and 
algorithms are separated, too, etc... However, I have no idea when 
anyone will have the time to actually implement that :-(


On Thu, 23 Apr 2009, Matthew Galati wrote:

> Currently OSI does support the branchAndBound function to solve a MILP.
> However, I don't see any access methods for MILP statistics afterwards (or
> any other MILP-type manipulation methods). Is there any intention to add
> this? For example, how do I get the number of nodes used, the gap, how do I
> set options specific to MILP for say, Cplex or Xpress calls?
> I can always cast an Osi to an OsiCpx and then get CpxLp and CpxEnv ptrs and
> then use Cpx directly -- but obviously all of this defeats the purpose of
> having OSI.
> Thanks,
> Matt

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