Originally posted by: SystemAdmin

Dear all,

I have some questions regarding to the node log. When I switch to traditional B&B method to solve my problem, I found in the column of B, there were several "X" which is not explained in the section of Progress Report: interpreting the node log in the the manual. I guess it might mean "N/A", because when it has an "X" under this column, there were nothing under the column "Variable". i.e. :

1010   170    21927.0541   504    26188.5474    21579.1107    85462   17.60%                 X   1010   1008    204
   1011   169    infeasible          26188.5474    21579.1107    85462   17.60%                 X   1011   1010    205
   1012   170    21927.0541   506    26188.5474    21579.1107    85465   17.60%                 X   1012   1010    205
   1013   171    21927.0636   512    26188.5474    21579.1107    85478   17.60%                 X   1013   1012    206
   1014   172    21927.0636   512    26188.5474    21579.1107    85479   17.60%                 X   1014   1013    207
   1015   171    infeasible          26188.5474    21579.1107    85479   17.60%                 X   1015   1014    208
   1016   172    21931.9149   520    26188.5474    21579.1107    85720   17.60%                 X   1016   1014    208
   1017   171    infeasible          26188.5474    21579.1107    85720   17.60%                 X   1017   1016    209
   1018   172    21966.6741   498    26188.5474    21579.1107    85863   17.60%                 X   1018   1016    209
   1019   173    21967.4816   513    26188.5474    21579.1107    85926   17.60%                 X   1019   1018    210
   1020   174    21968.1759   532    26188.5474    21579.1107    86141   17.60%                 X   1020   1019    211
Elapsed time = 999.02 sec. (tree size =  1.26 MB, solutions = 1)
   1021   175    21968.1759   532    26188.5474    21579.1107    86141   17.60%                 X   1021   1020    212
   1022   176    21968.1759   532    26188.5474    21579.1107    86141   17.60%                 X   1022   1021    213
   1023   177    21968.1759   532    26188.5474    21579.1107    86141   17.60%                 X   1023   1022    214
   1024   178    21968.1794   532    26188.5474    21579.1107    86161   17.60%                 X   1024   1023    215
   1025   179    21968.1794   532    26188.5474    21579.1107    86162   17.60%                 X   1025   1024    216
   1026   180    21968.1876   532    26188.5474    21579.1107    86179   17.60%                 X   1026   1025    217
   1027   181    21968.1876   532    26188.5474    21579.1107    86180   17.60%                 X   1027   1026    218
   1028   182    21968.1876   532    26188.5474    21579.1107    86181   17.60%                 X   1028   1027    219
   1029   183    21968.2380   512    26188.5474    21579.1107    86232   17.60%                 X   1029   1028    220
   1030   184    21968.2380   512    26188.5474    21579.1107    86233   17.60%                 X   1030   1029    221
   1031   185    21968.2380   512    26188.5474    21579.1107    86234   17.60%                 X   1031   1030    222
   1032   186    21968.6305   549    26188.5474    21579.1107    86262   17.60%                 X   1032   1031    223
   1033   187    21968.6305   549    26188.5474    21579.1107    86262   17.60%                 X   1033   1032    224
   1034   188    21968.6305   549    26188.5474    21579.1107    86262   17.60%                 X   1034   1033    225

Would anyone confirm my guess? Thanks.
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Originally posted by: SystemAdmin

Are you running in default settings? Are you using any callbacks.
The 'X' indicates that some branching is going on that is not CPLEX "default" branching.
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Originally posted by: SystemAdmin

Thank you for your reply. Yes, I am using goal to branch and bound myself. So is it possible to know what variable I am branching and bound by using any method of Goal? Thanks a lot.

A further question, in the section of comparison of goal and callback in the manual, it says that these two could realize the same functions except that the callback could take the advantage of advanced presolve processing. So if I just would like to branch and bound myself, and the advanced presolve processing has no significant impact on my problem, either way is Okay to do that?

Thanks.
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: SystemAdmin

CPLEX does not provide any functions to figure out the variable on which the branch at the current node was performed. However, it is relatively easy to implement a branch callback that keeps track of that information.
Similarly, using your own branching goal you can track that information. Note that in either case (goal and callback) it is easy to query the branches that CPLEX would perform, so you can branch exactly as CPLEX would do.
In this thread I posted example code for a goal that keeps track of the variables on which it branched.

Yes, is you just want to do branch-and-bound then either goals or callbacks are fine.
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