On the parameters of Goppa codes

A proof of V.D. Goppa's (1983) lower bound to the dimension of subfield subcodes of his geometric codes is given. A result on the minimum distance of these subfield subcodes is also given that generalizes the well-known bound: minimum distance of Gamma (L,G)>or=2 deg(G(X))+1 for classical Goppa codes Gamma (L,G) over the field F/sub 2/ with a square-free Goppa polynomial G=G(X).<
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