# How to write this constraint in Gurobi python?

I'm wondering how I can translate this math constraint to gurobi python.

$$\forall a \in A, b \in B, x_{ab} \in \{0, 1\}$$

So far I have written:

xab = m.addVar(lb=0, ub=1, vtype=GRB.BINARY, name="xab")


But I'm not sure what to add for the constraints section...

m.addConstr(?? for a in A for b in B, "c0")


Is it really as simple as replacing ?? with xab? Any help would be appreciated! Thanks

from gurobipy import *
A = []; B = [] # You need to enter the data in these lists

m = Model()
x = {} # Dictionary of variables
for a in A:
for b in B:
x[a, b] = m.addVar(lb=0, ub=1, vtype=GRB.BINARY, name="x_" +str(a) + str(b))



Note: Adding binary variables would constrain them to take values either 0 or 1. To add constraints involving these variables, you can use the following example syntax:

m.addConstr(x[a1, b1] + x[a2, b2] <= 10, name = 'c0')

• This is a good starting point but it seems that the OP question was mainly about how to add constraints to a Gurobi model. Mar 20 '21 at 17:55
• I'm confused. Does this edit address the issue? Mar 20 '21 at 20:24
• Thank you very much for improving your answer. I think it is more informative now. Even better would be to show how to set a constraint with the number of operands depending on the problem's input data. Mar 22 '21 at 10:33