On the dimension of subfield subcodes

Abstract

A new lower bound for the dimension of a subfield subcode is given. This bound improves the well-known lower bound of P. Delsarte (1975) and coincides in many cases with the true dimension of the code. Alternant codes and geometric Goppa codes are discussed as special cases.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>