How to model constraint to send only when facility is open?

Answered

Tanmoy Das

February 16, 2023 00:09 Edited

• 
• 
• 

Hi,

How can I implement a constraint so that resources from facility is sent to customer only when that facility is open? 

select is a binary variable to send resource r from station s. deploy is a continuous variable (not fractional from 0 to 1). I want to send resources only when s is open. From literature & gurobi example, I formulated the following. But, now the value of deploy is always less than 1. deploy should be equal to demands in customer points, e.g. 45. 

model2.addConstrs((deploy[s, o, r] <= select[s, r]  
                                     for o in OilSpills for s in Stations for r in ResourcesD),
                                    name='open_facility')

 

Related to

• Python

0

• 

  Riley Clement

  • Gurobi Staff

  February 17, 2023 12:57

  Hi Tanmoy,

  If select[s, r] is a binary variable, then it can be no larger than 1.  Consequently a constraint 

  deploy[s, o, r] <= select[s, r]

  would mean that deploy[s, o, r] could also not be larger than 1 as you have discovered.  If you were to instead use the constraint

  deploy[s, o, r] <= M*select[s, r]

  For some constant value M, then it would allow deploy[s, o, r] to have a value up to M whenever select[s, r].  I will leave it to you to decide what your M values should be, but my advice is not to make them any larger than they need to be.

  - Riley

  0

Please sign in to leave a comment.