On the uniqueness of (<Emphasis Type="Italic">p</Emphasis>, <Emphasis Type="Italic">h</Emphasis>)-gonal automorphisms of Riemann surfaces

Let X be a compact Riemann surface of genus g ≥  2. A cyclic subgroup of prime order p of Aut(X) is called properly (p, h)-gonal if it has a fixed point and the quotient surface has genus h. We show that if p > 6h + 6, then a properly (p, h)-gonal subgroup of Aut(X) is unique. We also discuss some related results.