[Dip] MILPBlock example causing "Point violates row"

[Matthew Galati]

Fixed: https://projects.coin-or.org/Dip/ticket/59

Thanks,
Matt

> -----Original Message-----
> From: dip-bounces at list.coin-or.org [mailto:dip-bounces at list.coin-or.org]
> On Behalf Of kim
> Sent: Thursday, December 02, 2010 3:19 AM
> To: Dip at list.coin-or.org
> Subject: [Dip] MILPBlock example causing "Point violates row"
> 
> I am getting some rather large violations with the unmodified MILPBlock
> example:
> "Point violates row 2 -> r(2) LB= 0.0000000 ax= -1017.0750594 UB=  INF
> RelViol= 1017.0750594"
> 
> This happened with an unmodified MILPBlock example, the "harp2"
> instance from miplib and the block file (list format):
> "0 74
> 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
> 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
> 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 106 111"
> 
> Constraints 0-71 and 111 are Special Ordeded Sets (\sum x_i  = 1) and
> constraint 106 is a degenerated 0-1 Knapsack constraint (capacity = 0)
> covering only a subset of the columns covered by the SOS constraints. I am
> auto generating my block files so it may not be a very good decomposition,
> but MILPBlock responds oddly and I cannot figure out why.
> The knapsack constraint simply fixes some variables to zero, and the
> remaining SOS constraints should not be that problematic. The problem is
> bounded, if nothing else then because all variables are binary.
> 
> Kim Vejlin
> 
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