A binary variable can be used to ensure that at least one out of two constraints must be satisfied, but not necessarily both. Define Y as a binary variable and incorporate it into the constraints below so that both constraints could be entered into a mixed IP model but only one of them would have to be satisfied in the optimal solution. Define M as a very large number and use it in both constraints.

Either 3A + 2B ≤ 18
or A + 4B ≤ 16