I have a model with lots of variables indexed over a few sets.
After having introduced the model, i.e. having already said that $x_{zt}$ has indexes $z\in Z$ and $t\in T$, instead of writing
"we consider the variables $x_{zt}$..."
or
" we consider the variables $x_{zt}$, with $z\in Z,\, t\in T$"
I tend to use
" we consider the variables $\{x_{zt}\}_{Z\times T}$"
I know the indexes are usually repeated in the subscript, e.g. it should be $\{x_{zt}\}_{(z,t)\in Z\times T}$, but I saw this done only when there was a single index; furthermore it would take longer to write and would be hard to read.
I think the notation I'm using is a good compromise, would you agree?
TIA
