Succinct notation for the set of largest equivalence classes of a set

Question

Let $S $ be any set and $R\subseteq S \times S$ be an equivalence realation on $S$.

I would like to express succinctly that set $W$ is any of the largest $R$-equivalence classes of $S$.

Is there any more succinct notation than the following two?

1. $ U = \{ T \in 2^S \mid \forall a,b \in T: (a,b) \in R \} $
   $ W = \textit{any set in} \arg \max_{V \in U}|V| $

2. $ W = \textit{any set in} \arg \max_{V \in \{ T \in 2^S \mid \forall a,b \in T: (a,b) \in R \}}|V| $