%0 Journal Article %T Genus calculations for towers of function fields arising from equations of $C_{ab}$ curves %A Caleb McKinley Shor %J Albanian Journal of Mathematics %D 2011 %I AulonaPress %X We give a generalization of error-correcting code construction from $C_{ab}$ curves by working with towers of algebraic function fields. The towers are constructed recursively, using defining equations of $C_{ab}$ curves. In order to estimate the parameters of the corresponding one-point Goppa codes, one needs to calculate the genus. Instead of using the Hurwitz genus formula, for which one needs to know about ramification behavior, we use the Riemann-Roch theorem to get an upper bound for the genus by counting the number of Weierstrass gap numbers associated to a particular divisor. We provide a family of examples of towers which meet the bound. %U http://journals.aulonapress.com/index.php/ajm/article/view/379/408