[Cbc] Suboptimal solution as optimal?

[John Forrest]

Ryan,

Bug in Cbc.  My first try gave correct result, but I managed to get 
error.  For small problems, Cbc will do a simpler faster branch and 
bound on a portion of the tree.  This is returning infeasible - I will 
look into it.

If you add -depth -100 (which means only go into this simpler version at 
depth 100) then all looked fine.

John Forrest
On 27/12/17 18:37, Rhavar wrote:
> I have a problem:
> https://gist.github.com/RHavar/dfb9de631363ecb9e1c326fff5ebd09b
>
> (lp file and solution file attached)
>
> In the solution it says: "Optimal - objective value"  but I think I 
> have found a superior solution by hand:
>
> o6 = 1
> i22 = 1
>
> Which gives a better objective (70 instead of 825)
>
> --
>
> So I guess my question is, does "Optimal - objective value" mean that 
> it's guaranteed to be the optimal solution? Or am I doing something 
> wrong? Or is there a bug in cbc?
>
>
> -Ryan
>
>
>
>
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