Nested Witt vectors and their q-deformation

초록

Let N subset of N be a truncation set. We study the ring of N-nested Witt vectors and its q-deformation. Given two arbitrary integers q and r, we provide a necessary and sufficient condition of A so that W-N(q) (A) and W-N(r) (A) should be strictly isomorphic to each other. Also, an isomorphism of functors, W-N(q) o W-M(q) congruent to W-MN(q), will be established for coprime truncation sets M and N. As a byproduct, we deal with interesting connections between nested Witt-vectors and other areas such as generalized Mobius mu-functions and numerical polynomials, i.e., polynomials which take integral values at integer arguments. (c) 2006 Elsevier Inc. All rights reserved.

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