6
$\begingroup$

Theorem (Weinstein - Synge) Let $(M,g)$ be a compact oriented positively curved $n$-dimensional Riemannian manifold. Supose $f$ is an isometry that preserves orientation if $n$ is even or reverses it if $n$ is odd. Then $f$ has a fixed point.

This result is also true for conformal diffeomorphisms and implies classical Synge's theorem for compact manifolds. Using the celebrated Soul Theorem we see that the compactness hypotesis in Synge's theorem can be replaced by completness.

Question Can we do the same on Weinstein's theorem?

Thanks!

PS: the even-dimensional version of Synge's theorem is that a compact positively curved oriented even-dimensional Riemannian manifold be simply connected.

Improve this question
$\endgroup$

1 Answer 1

Reset to default
8
$\begingroup$

The isometry group of a complete open connected manifold of positive sectional curvature has a fixed point. This is stated in Corollary 6.3 of the paper by Cheeger-Gromoll where they prove the soul theorem [Ann. of Math, 1972].

Improve this answer
$\endgroup$
2
  • $\begingroup$ Igor, you meant positive rather than nonnegative sectional curvature. $\endgroup$
    – Vitali Kapovitch
    Commented Jan 20, 2012 at 1:53
  • $\begingroup$ Yes, I just noticed the typo. $\endgroup$
    – Igor Belegradek
    Commented Jan 20, 2012 at 2:11

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .