\begin{definition}[Definition:Coset/Right Coset]
Let $\struct {S, \circ}$ be an algebraic structure.
Let $\struct {H, \circ}$ be a subgroup of $\struct {S, \circ}$.
The '''right coset of $y$ modulo $H$''', or '''right coset of $H$ by $y$''', is:
:$H \circ y = \set {x \in S: \exists h \in H: x = h \circ y}$
That is, it is the subset product with singleton:
:$H \circ y = H \circ \set y$
\end{definition}