[SCIP] How to access best dual sol in MIP case

[Benjamin Müller]

Dear Ahmad,

correct me if I am wrong but could it be that you seek for some kind of 
"dual" solution with the same objective value as the optimal solution of 
your MIP? This can be achieved by fixing all integer variables to the 
same value as in the optimal solution and solve the remaining LP to 
optimality.

If you really want to keep track of the dual solutions found after 
solving some LP relaxations you could implement an event handler 
(http://scip.zib.de/doc/html/EVENT.php) and catch the event 
SCIP_EVENTTYPE_LPSOLVED and then store / update the best dual solution 
in your data structure. Please note that not every optimal solution is 
found by solving some LP relaxation (if you use heuristics).

I guess it would be easier for us to help you if we know what do you 
want to do with those LP solutions.


Best,
Benny

On 06/13/2016 11:41 PM, Ahmad Moradi wrote:
> Dear SCIP community,
>
> I am working on a MIP and I need to look at the best dual sol found.
> As the best dual sol is the optimal solution found in a node's LP
> relaxation, I actually need to have access to primal variable's value in
> that LP. Or may I even have access to the best node's LP relaxation itself?
>
> Bests, Ahmad
>
>
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Benjamin Müller
Zuse Institute Berlin
Takustr. 7, 14195 Berlin
benjamin.mueller at zib.de
+49 30 841 85-195