Symmetric Homology of Algebras

TL;DR

This paper develops new methods to compute symmetric homology of algebras, relating it to stable homotopy theory and introducing spectral sequences and complexes that facilitate calculations.

Contribution

It introduces two chain complexes and spectral sequences for symmetric homology, connecting it to stable homotopy theory and the cycle-free chessboard complex.

Findings

Finite-dimensionality of symmetric homology groups for finite-dimensional algebras.

Construction of spectral sequences to aid in symmetric homology computations.

Partial resolution enabling computation of HS_1 for finite-dimensional algebras.

Abstract

The symmetric homology of a unital algebra $A$ over a commutative ground ring $k$ is defined using derived functors and the symmetric bar construction of Fiedorowicz. For a group ring $A = k[\Gamma]$, the symmetric homology is related to stable homotopy theory via $HS_*(k[\Gamma]) \cong H_*(\Omega\Omega^{\infty} S^{\infty}(B\Gamma); k)$. Two chain complexes that compute $HS_*(A)$ are constructed, both making use of a symmetric monoidal category $\Delta S_+$ containing $\Delta S$. Two spectral sequences are found that aid in computing symmetric homology. The second spectral sequence is defined in terms of a family of complexes, $Sym^{(p)}_*$. $Sym^{(p)}$ is isomorphic to the suspension of the cycle-free chessboard complex $\Omega_{p+1}$ of Vre\'{c}ica and \v{Z}ivaljevi\'{c}, and so recent results on the connectivity of $\Omega_n$ imply finite-dimensionality of the symmetric homology groups of finite-dimensional algebras. Some results about the $k\Sigma_{p+1}$--module structure of $Sym^{(p)}$ are devloped. A partial resolution is found that allows computation of $HS_1(A)$ for finite-dimensional $A$ and some concrete computations are included.