Condition within a condition in constraint

ユーザーの入力を待っています。

Syed Saad Ali

2021年09月13日 11:09

• 
• 
• 

How could I model my constraints in general and implement in Python Gurobi with the following conditions:

when \(q=0 \rightarrow y=0\) and when \(q=1\),

\[\begin{equation}
y = \begin{cases}
d & \mathrm{if }\; d\leq b\\
b & \mathrm{otherwise.}
\end{cases}
\end{equation}\]
where \(q\) is a binary variable, \(y\) is a continuous variable and \(b\), \(d\) are constants.

 

0

• 正式なコメント

  

  Simranjit Kaur

  • Gurobi Staff

  2024年12月06日 00:26

  This post is more than three years old. Some information may not be up to date. For current information, please check the Gurobi Documentation or Knowledge Base. If you need more help, please create a new post in the community forum. Or why not try our AI Gurobot?.
• 

  Jaromił Najman

  • Gurobi Staff

  2021年09月14日 07:57

  If \(b,d\) are constants, you could determine whether \(d\leq b\) a priori and then implement your condition as

  d = 5
  b = 4
  a = min(b,d)
  q = m.addVar(vtype=GRB.BINARY,name="q")
  y = m.addVar(vtype=GRB.CONTINUOUS,name="y")
  m.addConstr(y == q * a)

  Best regards,
  Jaromił

  0
• 

  Syed Saad Ali

  2021年09月16日 05:06

  • 
  • 
  • 

  Hi Jaromil,

  these $b$ and $d$ aren't known a priori and are in the form of a list.

  0
• 

  Jaromił Najman

  • Gurobi Staff

  2021年09月16日 07:51

  Hi Syed,

  In this case, could you elaborate more on the nature of the \(b\) and \(d\) terms? If they are both constant parameters, then both values should be available when the model is constructed. Otherwise they depend on the values of some other optimization variables making \(b\) and \(d\) optimization variables as well. How does the fact that \(b,d\) are lists take effect here? Do you actually want to introduce multiple constraints of the above form or do you want to check whether all values in \(d\) are \(\leq\) than \(b\)?

  Best regards,
  Jaromił

   

  0

投稿コメントは受け付けていません。