[Scip] GCG heuristics - error "selected node is neither sibling, child, nor leaf"

Christian Puchert c.puchert at stud.tu-darmstadt.de
Wed Jul 14 15:08:23 MEST 2010


Hi all,

I am currently working on Gerald Gamrath's GCG 0.8.0 (which performs a
Dantzig-Wolfe decomposition and solves it with Branch and Price). At the
moment, I am trying to re-implement the existing SCIP heuristics such
that they are able to run on the original x variables, i.e. on the
original MIP. Gerald has already re-implemented Rounding, and I tried to
do the same with Shifting and RENS. My heuristics are indeed able to
find feasible solutions for some MIPs; however, I sometimes get an error
message like this:

[src/scip/tree.c:3818] ERROR: selected node is neither sibling, child,
nor leaf (nodetype=8)
[src/scip/solve.c:3157] ERROR: Error <-9> in function call
[src/scip/scip.c:5592] ERROR: Error <-9> in function call
[src/relax_gcg.c:1184] ERROR: Error <-9> in function call
[src/scip/relax.c:268] ERROR: Error <-9> in function call
[src/scip/solve.c:1968] ERROR: Error <-9> in function call
[src/scip/solve.c:2560] ERROR: Error <-9> in function call
[src/scip/solve.c:3192] ERROR: Error <-9> in function call
[src/scip/scip.c:5592] ERROR: Error <-9> in function call
[src/dialog_gcg.c:987] ERROR: Error <-9> in function call
[src/scip/dialog.c:791] ERROR: Error <-9> in function call
[src/scip/dialog.c:335] ERROR: Error <-9> in function call
[src/scip/scip.c:2566] ERROR: Error <-9> in function call
[src/scip/scipshell.c:346] ERROR: Error <-9> in function call
[src/main.c:53] ERROR: Error <-9> in function call
SCIP Error (-9): method cannot be called with this type of data

(A short look at type_tree.h reveals that nodetype 8 stands for "fork".)

My heuristics make use of the methods SCIPlinkRelaxSol (Shifting) and
GCGrelaxGetCurrentOrigSol (RENS), respectively, in order to get an LP
feasible solution to which they can be applied.

I am working with GCG 0.8.0 together with SCIP 1.2.0.8 and SoPlex 1.4.2
as LP solver.

Has anyone got an idea what may be the cause of this error? If you wish,
I can send you my code.

Thanks and regards,
Christian


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