In: Advanced Math
Let R be a commutative domain, and let I be a prime ideal of R.
(i) Show that S defined as R \ I (the complement of I in R) is multiplicatively closed.
(ii) By (i), we can construct the ring R1 = S-1R, as in the course. Let D = R / I. Show that
the ideal of R1 generated by I, that is, IR1, is maximal, and R1 / I1R is isomorphic to the
field of fractions of D. (Hint: use the fact that everything in S-1R can be written in the
form s-1r, where s ∈ S and r ∈ R. The first step is to show that IR1 ∩ R = I).