For a not-necessarily commutative ring R we define an abelian group W(R;M) of Witt vectors with coefficients in an R-bimodule M. These groups generalize the usual big Witt vectors of commutative rings and we prove that they have analogous formal properties and structure. One main result is that W(R) ∶= W(R;R) is Morita invariant in R. For an R-linear endomorphism f of a finitely generated projective R-module we define a characteristic element χf ∈ W(R). This element is a non-commutative analogue of the classical characteristic polynomial and we show that it has similar properties. The assignment f ↦ χf induces an isomorphism between a suitable completion of cyclic K-theory K cyc0 (R) and W(R).
|Number of pages||43|
|Early online date||26 Apr 2022|
|Publication status||Published - 26 Apr 2022|
- Witt vectors
- characteristic polynomial