\title[derived equivalences and Reynolds ideals]{Invariance of generalised Reynolds ideals\\ under derived equivalences} \author[Alexander Zimmermann]{Alexander Zimmermann} \address{Universit\'e de Picardie,\newline Facult\'e de Math\'ematiques et LAMFA (UMR 6140 du CNRS),\newline 33 rue St Leu, \newline F-80039 Amiens Cedex 1, \newline France} Accepted in the MATHEMATICAL PROCEEDINGS OF THE ROYAL IRISH ACADEMY http://www.ria.ie/publications/journals/procai/index.html \begin{abstract} For any algebraically closed field $k$ of positive characteristic $p$ and any non negative integer $n$ K\"ulshammer defined ideals $T_nA^\perp$ of the centre of a symmetric $k$-algebra $A$. We show that for derived equivalent algebras $A$ and $B$ there is an isomorphism of the centres of $A$ and $B$ mapping $T_nA^\perp$ to $T_nB^\perp$ for all $n$. Recently H\'ethelyi, Horv\'ath, K\"ulshammer and Murray showed that this holds for Morita equivalent algebras. \end{abstract}