# Equivariant $A$-Theory

### Cary Malkiewich

Department of Mathematics, University of Binghamton, Binghamton, New York, USA### Mona Merling

Department of Mathematics, University of Pennsylvania, Philadelphia, Pennsylvania, USA

## Abstract

We give a new construction of the equivariant $K$-theory of group actions [*C. Barwick*, “Spectral Mackey functors and equivariant algebraic $K$-theory (I)”, Adv. Math. 304, 646–727 (2017; Zbl 1348.18020) and *C. Barwick* et al., “Spectral Mackey functors and equivariant algebraic $K$-theory (II)”, Preprint (2015); arXiv:1505.03098], producing an infinite loop $G$-space for each Waldhausen category with $G$-action, for a finite group $G$. On the category $R(X)$ of retractive spaces over a $G$-space $X$, this produces an equivariant lift of Waldhausen's functor $A(X)$, and we show that the $H$-fixed points are the bivariant $A$-theory of the fibration $X_{hH}→BH$. We then use the framework of spectral Mackey functors to produce a second equivariant refinement $A_{G}(X)$ whose fixed points have tom Dieck type splittings. We expect this second definition to be suitable for an equivariant generalization of the parametrized $h$-cobordism theorem.

## Cite this article

Cary Malkiewich, Mona Merling, Equivariant $A$-Theory. Doc. Math. 24 (2019), pp. 815–855

DOI 10.4171/DM/694