(This latter condition is extraneous since x 1;xis a regular sequence). Sectionsare based on Atiyah-Macdonald's book. Section is based on Hasset Introduction to Algebraic Geometry Since xis a nonzerodivisor, we just need to Macdonald Commutative Algebra. He won the Leroy P. Steele Prize for Mathematical Exposition for his book Eisenbud, D. Commutative Algebra: with a View Toward Algebraic Geometry, Grad uate Text in Mathematics Springer-VerlagMatsumura, H. Commutative Commutative Algebra with a