Commutative Algebra, IX, p. 50
Let r1,r2,n be integers satisfying
1⩽r1⩽r2⩽n. Let
T1,...,Tn be indeterminates. By arguments analogous to those of the preceding exercise, give a description of the ring of Witt vectors over the ring
k[T1,...,Tr1,T1−1,...,Tr1−1,Tr1+1,...,Tr2][[Tr2+1,...,Tn]].