Differential algebra of polytopes and inversion formulas

We use the differential algebra of simple polytopes to explain the remarkable relation of the combinatorics of the associahedra and permutohedra with the compositional and multiplicative inversion of formal power series. This approach allows to single out the associahedra and permutohedra among all graph-associahedra and emphasizes the significance of the differential equations for polytopes derived earlier by one of the authors. We discuss also the link with the geometry of Deligne-Mumford moduli spaces M₀, ₍ and provide a new interpretation of the combinatorics of cyclohedra in relation with the classical Fa\`a di Bruno's formula.