  In this paper, we firstly point out, by a counter example, that Proposition
6.4 of Section 6 in Bump's book (Algebraic Geometry) is error, and then give a
correct statement with proof. We finally point out a gap in the proof of
Theorem 3, in Chapter I Section 8, of Mumford's red book, and indicate a way to
complete it.

Algebraic Geometry