This has H = 1
- Consider . If is in the clsoure (taken in ), then extend by zero.
- Otherwise is not in the closure, argue for a sufficiently small disjoint from
- Argue in fact ; for all , near
- If use to show ; contradiction.
- By the above, conclude .
- Use the determinant trick to show is integral over .
Determinant Trick: Let be a finitely generated (say by elements) module and be endomorphism such that there is an ideal such that , then satifies a monic polynomial relation of degree .