Forward circle minus
From timescalewiki
Let $\mathbb{T}$ be a time scale and let $p,q \in \mathcal{R}(\mathbb{T},\mathbb{C})$ be (forward) regressive functions . We define the (forward) circle minus operation by $$\left( \ominus_{\mu} p \right)(t) = \dfrac{-p(t)}{1+p(t)\mu(t)}.$$ Often in the literature, the subscript is suppressed.
Properties
Forward regressive functions form a group
Circle minus inverse of circle plus