Equivalent formulations of the Riemann hypothesis based on lines of constant phase

Abstract

We prove the equivalence of three formulations of the Riemann hypothesis for functions f defined by the four assumptions: (a1) f satisfies the functional equation f (1 - s) = f (s) for the complex argument s = sigma + i tau, (a2) f is free of any pole, (a3) for large positive values of s the phase. of f increases in a monotonic way without a bound as tau increases, and (a4) the zeros of f as well as of the first derivative f ' of f are simple zeros. The three equivalent formulations are: (R1) All zeros of f are located on the critical line sigma = 1/2, (R2) All lines of constant phase theta of f corresponding to +/-pi, +/- 2 pi, +/- 3 pi, ... merge with the critical line, and (R3) All points where f' vanishes are located on the critical line, and the phases of f at two consecutive zeros of f' differ by pi. Our proof relies on the topology of the lines of constant phase of f dictated by complex analysis and the assumptions (a1)-(a4). Moreover, we show that (R2) implies (R1) even in the absence of (a4). In this case (a4) is a consequence of (R2).