[Scip] finding cutting planes is scip2.0.1 and scip2.1.0

[James Cussens]

I have a constraint handler which includes some code for finding
cutting planes for a machine learning problem (Bayesian net learning).
With SCIP 2.0.1 this works well. The routine for finding the cutting
planes (a sub-MIP which uses a depth-first search, no linear
relaxation finds (usually several) good cutting planes. Moving to SCIP
2.1.0 the story is very different. On even very easy problems vast
numbers of useless cutting planes are found.

The two attached files tell the story. With SCIP 2.0.1 13 cutting
planes are enough to solve the problem. With SCIP 2.1.0 I had to
terminate the process after very many (mostly bad) cutting planes had
been generated.

My code is the same in both cases, except to account for the extra
constraint handler argument in SCIP 2.1.0. The attached files were
produced just after a fresh install of the two SCIPs just to be sure.

Perhaps there is a simple explanation. Some crucial change to a
default value, perhaps.

Any ideas? I'm happy to send out my source(s) if that would help anyone.

-- 
James Cussens
Dept of Computer Science &
York Centre for Complex Systems Analysis
Room 326, The Hub, Deramore Lane            Tel    +44 (0)1904 325371
University of York                                        Fax  +44
(0)1904 500159
York YO10 5GE, UK                               http://www.cs.york.ac.uk/~jc
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