Published online by Cambridge University Press: 28 January 2016
Let $G$ be a connected nilpotent Lie group with a continuous local action on a real surface $M$, which might be non-compact or have non-empty boundary $\unicode[STIX]{x2202}M$. The action need not be smooth. Let $\unicode[STIX]{x1D711}$ be the local flow on $M$ induced by the action of some one-parameter subgroup. Assume $K$ is a compact set of fixed points of $\unicode[STIX]{x1D711}$ and $U$ is a neighborhood of $K$ containing no other fixed points.
Theorem.If the Dold fixed-point index of$\unicode[STIX]{x1D711}_{t}|U$is non-zero for sufficiently small$t>0$, then$\mathsf{Fix}(G)\cap K\neq \varnothing$.