The Weierstrass semigroups on double covers of genus two curves

Abstract

We show that three numerical semigroups $\langle 5, 6, 7, 8\rangle, \langle3, 7, 8\rangle$ and $\langle 3, 5\rangle$ are of double covering type, i.e., the Weierstrass semigroups of ramification points on double covers of curves. Combining the result with [7] and [4] we can determine the Weierstrass semigroups of the ramification points on double covers of genus two curves.