Second-Order Parameterizations for the Complexity Theory of Integrable Functions

We develop a unified second-order parameterized complexity theory for spaces of integrable functions. This generalizes the well-established case of second-order parameterized complexity theory for spaces of continuous functions. Specifically we prove the mutual linear equivalence of three natural parameterizations of the space $\text{Lrm}p$ of $p$-integrable complex functions on the real unit interval: (binary) $\text{Lrm}p$-modulus, rate of convergence of Fourier series, and rate of approximation by step functions.