Dear community,

I am working on a lot sizing problem with sequence dependent setupcosts for my thesis project. Since I have no particular background in e.g., operations research, some of the notations are unfamiliar to me. Consider the following constraint to eliminate subtours in the setup sequence between products (indexed with i and j) in a specific time period t.

𝑉𝑖𝑡 + 𝑁 ∙ 𝑇𝑖𝑗𝑡 − (𝑁 − 1) − 𝑁 ∙ 𝛼𝑖𝑡 ≤ 𝑉𝑗𝑡       ∀𝑖,𝑡,𝑗\{𝑖}

I do not understand how to implement the last part (𝑗\{𝑖}) in the index domain. 

I really appreciate your help!