Ondřej Toman

I found it. I can use  BARRIER_DUALOBJ in callback to get dual objective in each iteration. https://support.gurobi.com/hc/en-us/community/posts/4405814500241-ObjBound-Barrier-with-no-crossover

There is example of one simple model for which I am trying to get LB. NAME ROWS N  OBJ E  R0       E  R1       E  R2       E  R3       E  R4       E  R5       E  R6       E  R7       E  R8       E ...

Thanks, that worked. But why setting the OptimalityTol does not work?