A tail bound for cumulant series for complex functions of independent random variables

We obtain explicit bounds on the truncation error of the cumulant series of a bounded complex function of a random vector with independent components. The bounds are based on multidimensional differences. This extends the theory of the author with Brendan McKay and Rui-Ray Zhang (J. Combin. Th., Ser. B, 2025) from real functions to complex functions. We demonstrate some initial applications including a Berry--Esseen bound, an Edgeworth expansion for triangles in random graphs, and enumeration of regular graphs.