[Help-glpk] Patch for pseudocost branching with product score

[Chris Matrakidis]

Hi Andrew,

This patch adds the option to select the branching variable using
pseudocosts with product score, as described in Tobias Achterberg's
thesis [1]. This is selected with a new br_tech option (GLP_BR_PMH)
and a new option in glpsol (--pcostmul), so the old default behaviour
is preserved. The patch also updates the manual accordingly.

The patch is on top of the three initial patches I sent for
speeding-up pseudocost initialisation, but should apply even without
them.

Using "glpsol --pcostmul --cuts" I was able to solve the following 32
problems from the MIPLIB 2010 benchmark set: acc-tight5, air04,
app1-2, ash608gpia-3col, biella1, bienst2, binkar10_1, core2536-691,
dfn-gwin-UUM, eil33-2, eilB101, lectsched-4-obj, map18, map20,
mcsched, mine-166-5, neos-1109824, neos13, neos18, neos-476283,
neos-686190, ns1766074, opm2-z7-s2, qiu, ran16x16, rmatr100-p10,
rmatr100-p5, rmine6, sp98ir, tanglegram1, tanglegram2 and triptim1.


Best Regards,

Chris Matrakidis

[1] T. Achterberg, "Constraint Integer Programming," PhD thesis, TU
Berlin, 2007.

pcostmul.patch
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