A Diophantine generalization of Fourier's irrationality trick

Abstract

We revisit Fourier's method for proving the irrationality of $e$ and generalize it into a unified Diophantine framework, which applies to a broad class of series with bounded or mildly growing integer numerators, and suitably growing, divisible denominators. Using integer linear forms, we establish a general criterion that recovers classical irrationality results while also generating new ones within a single structural approach.