# Maurer–Cartan elements and cyclic operads

### Benjamin C. Ward

Stockholm University, Sweden

## Abstract

First we argue that many BV and homotopy BV structures, including both familiar and new examples, arise from a common underlying construction. The input of this construction is a cyclic operad along with a Maurer–Cartan element in an associated Lie algebra. Using this result we introduce and study the operad of cyclically invariant operations, with instances arising in cyclic cohomology and $S^1$ equivariant homology. We compute the homology of the cyclically invariant operations; the result being the homology operad of $\mathcal M_{0,n+1}$, the uncompactified moduli spaces of punctured Riemann spheres, which we call the gravity operad after Getzler. Motivated by the line of inquiry of Deligne’s conjecture we construct "cyclic brace operations" inducing the gravity relations up-to-homotopy on the cochain level. Motivated by string topology, we show such a gravity-BV pair is related by a long exact sequence. Examples and implications are discussed in course.

## Cite this article

Benjamin C. Ward, Maurer–Cartan elements and cyclic operads. J. Noncommut. Geom. 10 (2016), no. 4, pp. 1403–1464

DOI 10.4171/JNCG/263