[SCIP] Propagating constraints, rows and variables

[Rolf van der Hulst]

Hi,

I am working on a SCIP application with a branch-price-and-cut approach for
Graph Coloring. I used the coloring application from scip as my starting
point.

In the coloring application, in order to 'remove' a (non-negative) variable
x from the formulation,  the upper bound is simply changed to 0.0 in
propagation (see cons_storeGraph.c, ~line 706). Does calling
SCIPchgVarUB(scip,x,0.0) also ensure that the variable is removed from the
internal representation of the LP solver? Additionally, when calling this
in the B&B tree, is the variable enabled again after leaving the subtree of
the node that deactivated it?

SCIPdelConsNode() seems to work well for constraints, however I run into
some issues when trying to propagate cutting planes.
I also have a separator, where I add cuts using SCIPcreateEmptyRowSepa()
and SCIPaddRow(). How can I propagate these cuts? There is no interface as
there is for normal constraints. I have 'local' set to FALSE and
'removable' set to TRUE in SCIPcreateEmptyRowSepa();  If, due to domain
propagation of the variables, a cut no longer cuts off part of the relevant
problem, is the cut then automatically removed from the LP?

Best,

Rolf van der Hulst
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