Def. Let f : X y 1. A left inverse off is a function g : Y X such that, for all z g(f(x)) 2. 2. A right inverse of f is a function g : Y X such that, for all y E Y, f(g(y))-y. 3. An inverse of f is a function that is both a left inverse and a right inverse of f. Afunction f : X