© 1984 by London Mathematical Society
HEIGHT PLUS DIFFERENTIAL DIMENSION IN COMMUTATIVE NOETHERIAN RINGS
Department of Mathematics, University of Utah Salt Lake City, Utah 84112, U.S.A.
Received 20 June 1983.
Differential dimension and differential codimension for prime ideals in a commutative noetherian ring R equipped with commuting derivations
1,...,
u may be defined in terms of ranks of Jacobian matrices. Given prime ideals P
Q in R such that char (R/Q) = 0, it is proved that
diff.codim.(Q)diff.codim.(P)
ht(Q/P)
and that
ht(P) + diff.dim.(P)
ht(Q) + diff.dim.(Q).
Using the latter inequality, the known formulas for the global dimension and the Krull dimension of the formal differential operator ring R[
1,...,
u] are simplified.
Current address of 2nd author: Department of Mathematics, James Clerk Maxwell Building, The King's Buildings, Edinburgh EH9 3JZ.