# Forward regressive function

Let $\mathbb{T}$ be a time scale. Let $p \colon \mathbb{T} \rightarrow \mathbb{C}$. We say that $p$ is forward regressive if for all $t \in \mathbb{T}^{\kappa}$ $$1+\mu(t)p(t)\neq 0.$$ We call the set of forward regressive functions with domain $X$ and codomain $Y$ by $\mathcal{R}(X,Y)$.