Suppose that we have two functions $f : \mathbb{R}^2 \rightarrow \mathbb{R}$ and $g : \mathbb{R}^2 \rightarrow \mathbb{R}$ satisfying
$$ f(x, g(x, y)) = y \quad \forall x, y \in \mathbb{R}$$
They're not exactly inverses, but is there a specific name for the relationship between $f$ and $g$? If not, references to similar relationships would be much appreciated.