[Scip] How to solve the root LP associated to an MIP

[Martin Bergner]

Hello all,

I want to solve the LP associated to a given MIP before actually solving
the MIP (e.g. before calling SCIPsolve()). I suspected that I could call
constructLP and then solve that somehow. Unfortunately, I coud not
construct the LP both in the presolving and transforming stage.

What I did now, is that in a relaxation handler exec method I call
SCIPconstructLP / SCIPstartProbing / SCIPsolveProbingLP /
SCIPendProbing. I can access the dual variables associated to MIP
constraints, which works somehow.

However, I actually only want to solve the root LP of my main MIP and
then the (root) LPs associated to my subproblems. My current approach
would force me to implement a relaxator for the subproblems only to
construct the root LP, which seems to be quite awkward. 

So what is the canonical way to construct and solve the root LP of an
MIP before actually starting the branch and cut algorithm?

Unfortunately, I didn't find any suitable LP method in scip.h and
pub_lp.h that seem to to what I want.

Regards and thanks 
Martin

P.S.: I'm currently using scip 1.2.0.8.