# functional inverse of the Y-combinator

The Y-combinator is a higher order function that computes the fixed point of functions.

$Y(d/dx) = Aexp(x)$

Problem: what is the inverse Y-combinator here, viz, suppose we make the $d/dx$ the unknown,

how could I solve:

given

$Y(\xi) = Aexp(x)$, solve for $\xi$