VRP with breaks minor bug?

[vuongdanghuy]

What version of OR-Tools and what language are you using?
Version: stable branch
Language: C++

Which solver are you using (e.g. CP-SAT, Routing Solver, GLOP, BOP, Gurobi)
Routing Library

What operating system (Linux, Windows, ...) and version?
Linux Mint 21.3

What did you do?
Using VRP with breaks. GlobalVehicleBreaksConstraint will be added to the Solver.

What did you expect to see
I believe here we're updating StartMin value of the arc path_[pos] -> path_[pos + 1] to EndMin value of the break interval. This arc StartMin is CumulVar(path_[pos])->Min() - arc_start_offset. So instead of SetMin(CapSub(interval_end_min, arc_start_offset)) it should be SetMin(CapAdd(interval_end_min, arc_start_offset)).

or-tools/ortools/constraint_solver/routing_breaks.cc

Lines 943 to 951 in 5124f49

	// Interval not after.
	if (interval_start_max < arc_end_min) {
	interval->SetEndMax(arc_start_max);
	if (interval_is_performed) {
	dimension_->CumulVar(path_[pos])
	->SetMin(CapSub(interval_end_min, arc_start_offset));
	}
	}
	continue;

You are correct, this should be a CapAdd() instead of a CapSub().
The current SetMin() is weaker than it could be.
Thank you for the report!

[varshneydevansh]

So all we have to do is to replace the CapSub with the CapAdd ?

Or is there anything else which I should consider?

[vuongdanghuy]

yeah, replace CapSub by CapAdd will do

[varshneydevansh]

Okay creating a PR :)