REAL ANALYSIS EXCHANGE, vol.49, no.1, pp.189-204, 2024 (ESCI)
We consider the Volterra integration operator V, V f(x) = integral(x)(0) f(t) dt, on the following subspace of the Wiener algebra W[0, 1]: W-(1)[0, 1] := {f is an element of W[0, 1] : f' is an element of W[0, 1]}. We investigate solvability of the operator equations VA = lambda AV and VA = lambda A(2)V, where lambda is an element of C is a complex number. Our proof is based on the Duhamel product of functions defined by (f circle star g)(x) := d/dx integral(x)(0) f(x - t) g(t) dt.