Effective algebraicity for solutions of systems of functional equations with one catalytic variable

We study systems of $n\ge 1$ discrete differential equations of order $k\ge 1$ in one catalytic variable and provide a constructive and elementary proof of algebraicity of their solutions. This yields effective bounds and a systematic method for computing the minimal polynomials. Our approach is a generalization of the pioneering work by Bousquet-Mélou and Jehanne (2006).