Trace methods for coHochschild homology
摘要
Hochschild homology is a classical invariant of rings that plays an important role because of its connection to algebraic K-theory via the Dennis trace. At level zero, the Dennis trace is induced by the Hattori–Stallings trace. In this paper, we introduce new algebraic K-theories of coalgebras and obtain coalgebraic refinements of the Hattori–Stallings trace that connect these algebraic K-theories to coHochschild homology—the invariant analogous to Hochschild homology but for coalgebras. We employ bicategorical methods of Ponto to show that coHochschild homology is a shadow. Consequently, we obtain that coHochschild homology is Morita–Takeuchi invariant.