The depth-one decomposition hypothesis for solvable meromorphic equations

Let $X\subseteq\mathbb{C}$ be a connected open set and let $f:X\to\mathbb{C}$ be a meromorphic elementary function. A function is solvable when its equation with a constant right-hand side is solvable in elementary functions, and its depth is the notion used in the paper. Depth-one decomposition hypothesis. If the equation $f(x)=a$ is solvable in elementary functions, then there exists a finite sequence $g_1,g_2,\ldots,g_\ell$ of solvable functions of depth at most $1$ such that

$$f(x)=(g_1\circ g_2\circ\ldots\circ g_\ell)(x).$$

This hypothesis proposes that every elementary-solvable meromorphic equation admits a decomposition into solvable factors whose depth is at most one. The source presents it as a hypothesis based on modest computational evidence; its status is therefore open.