# Compactness and Index of Ordinary Central Configurations for the Curved $N$-Body Problem

*2021, Volume 26, Number 3, pp. 236-257*

Author(s):

**Zhu S.**

For the curved $n$-body problem, we show that the set of ordinary central configurations is away from singular configurations in $\mathbb{H}^3$ with positive momentum of inertia, and away from a subset of singular
configurations in $\mathbb{S}^3$. We also show that
each of the $n!/2$ geodesic ordinary central configurations for $n$ masses has Morse index $n-2$.
Then we get a direct corollary that there are at least $\frac{(3n-4)(n-1)!}{2}$ ordinary central
configurations for given $n$ masses if all ordinary central configurations of these masses are nondegenerate.

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