Séminaire Lotharingien de Combinatoire, B28c (1992), 7 pp.
[Formerly: Publ. I.R.M.A. Strasbourg, 1992, 498/S-28, p. 45-51.]

Andreas Dress and Christian Siebeneicher

On the Integrality of the Witt Polynomials

Abstract. Let rings denote the category of commutative rings with unity elements. Many functors F from rings to rings have the following property: char A=p implies that char F(A)=p. We construct a functor W G: rings -> rings, given a profinite group G. If G is the cyclic group with p elements, then W C p has the property that if char A=p, then char W C p(A) is different from p. We provide several additional results on properties of this functor, and study the functor for various groups G, in particular for the profinite completion of the infinite cyclic group.

The following version are available: