A 
-typical Witt vector over a commutative
ring 
is a sequence 
with addition and multiplication specified by universal integer
polynomials through the ghost components
 |
The operations make every ghost component a ring homomorphism. They are defined by these universal polynomials
even when the ghost map is not injective in 
. For a perfect field 
of characteristic 
, the Witt vector ring 
is a complete discrete
valuation ring of characteristic zero, with residue
field 
and uniformizer 
.
For example, 
.
Integral Donovan finiteness uses 
as its fixed coefficient ring.
