Python Cplex Constraint Programming Logical Constraint

Question

I am studying Cplex CP in Python, and I have two integer variables x and y.

I do some calculations and I find x's value, for example:

y = ..some calculations..

x = 3600 / y

I want to do this, If the x is lower than the 200(limit of x), x is 3600 / y. But, If the x is higher than the 200, x is 200.

I tried these expressions:

1:

((x >= limit_x) == limit_x ) or ((x <= limit_x) == 3600 / y )

1.revised:

((x >= limit_x) == limit_x ) and ((x <= limit_x) == 3600 / y )

2:

x == 3600 / y
x <= limit_x

3:

(x <= limit_x) == 3600 / y

I couldn't find any solution. I need your bits of help.

Best regards,

Alex Fleischer · Accepted Answer · 2022-04-12 14:42:17Z

0

Let me mix

disjuntion and Constraint Programming

And I get

from docplex.cp.model import CpoModel

mdl = CpoModel(name='buses')
nbbus40 = mdl.integer_var(0,1000,name='nbBus40')
nbbus30 = mdl.integer_var(0,1000,name='nbBus30')
mdl.add(nbbus40*40 + nbbus30*30 >= 300)

mdl.add(1==mdl.logical_or(nbbus40>=7,nbbus40<=3))
mdl.minimize(nbbus40*500 + nbbus30*400)

msol=mdl.solve()

print(msol[nbbus40]," buses 40 seats")
print(msol[nbbus30]," buses 30 seats")

that gives

3  buses 40 seats
6  buses 30 seats

edited Apr 12, 2022 at 14:42

answered Apr 12, 2022 at 14:34

Alex Fleischer

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2 Comments

Tunahan Bilgiç Over a year ago

Thank you for your answer Mr. Fleischer. I saw this example from your LinkedIn account, but I have some problems here. The value of x could be 0 or 3600 / y or the limit of x. Can I use the nested logical or?

Alex Fleischer Over a year ago

Sure. In my tiny example I can write mdl.add(1==mdl.logical_or(nbbus40>=10,mdl.logical_or(nbbus40==2,nbbus40==1)))

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