On large automorphism groups of algebraic curves in positive characteristic
arXiv:0706.2320
Abstract
In his investigation on large -automorphism groups of an algebraic curve, Stichtenoth obtained an upper bound on the order of the first ramification group of an algebraic curve $\cX$ defined over an algebraically closed field of characteristic . Stichtenoth's bound has raised the problem of classifying all $\K$-automorphism groups of $\cX$ with the following property: There is a point $P\in \cX$ for which \begin{equation} |G_P^{(1)}|>\frac{p}{p-1}g. \end{equation} Such a classification is obtained here by proving Theorem 1.3