Originally posted by: P4VU_Yacine_Laalaoui

Hi all,

Could someone explain to me the following cplex outputs in which the GAP equals 0 while the the optimal solution is different from the best bound ? If I understand I should get 20564 in the optimal solution instead of 20563 :

Node  Left     Objective  IInf  Best Integer    Best Bound    ItCnt     Gap

*     0+    0                            0.0000    24062.0000       57     --- 
      0     0    20565.2781     5        0.0000    20565.2781       57     --- 
      0     0    20564.8583     7        0.0000       Cuts: 4       81     --- 
      0     0    20564.0000     7        0.0000       Cuts: 2       86     --- 
      0     0    20564.0000     7        0.0000    MIRcuts: 1       87     --- 
      0     0    20564.0000     7        0.0000   ZeroHalf: 1       89     --- 
*     0+    0                        20563.0000    20564.0000       89    0.00%

OBJECTIVE: 20563

Thanks in advance

Yacine

Originally posted by: T_O

Here is my guess:

The difference is below 0.005% and thus rounded to 0.00% instead of 0.01%.

Originally posted by: Lessi

The default optimal gap is 10^-4, that is the reason why cplex declared 20563 as an optimal solution.