[Scip] Detecting specific constraint types from linear constraints

[Martin Bergner]

Hi Timo,

> If this is the case you can disable upgrading fore 
> certain constraints via the parameters:
> /set/constraints/linear/upgrade/{knapsack, setppc, logicor, varbound}
Ok, this might actually already help me.

> Or do you just want to test whether constraints might be upgraded, but without 
> performing the upgrade? If yes: why? ;-)
This is what I want. The reason is because I'm scared of the SCIP
internals :). And because of this, I want to do as little changes to the
problem as possible. My main objective is that I want to detect certain
types of problems which I know how to decompose and perform the
decomposition automatically (in a copy of the original scip instance).
It would simplify the problem a lot if I just knew that a particular
linear constraint is actually a knapsack.

> There is no explicit function that gives you this functionality.
> It should, however, not be to hard to implement the test on your own.
Yes, I know, but I thought since the functionality is already there and
the code is tested, I hoped that I wouldn't need to implement all checks
on my own. 

> I hope this helps you with your question.
It did, yes.

FYI, I implemented it at the moment as 
1. Call consLinearUpgrade
2. Find type of constraintHandler
3. release upgdcons

I think it is a little bit ugly, but it seems to serve its purpose.

Thanks a lot,
Martin