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5 votes
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Conditions on the hierarchy for Thurston's hyperbolization theorem

Yes, there are conditions; basically you want to maintain the hypothesis of not having incompressible annuli at each stage. A really good reference for this is Morgan's essay, "On Thurston's uniformiz …
Danny Ruberman's user avatar
18 votes
Accepted

Topological rigidity for negatively curved manifolds?

I'm assuming that your intention is that negatively curved means having negative sectional curvature. Your question, with regard to uniqueness up to homeomorphism, is a special case of the Borel Conj …
Danny Ruberman's user avatar
6 votes

Residual finiteness of hyperbolic 3-manifold groups

Here's another negative answer for Q2. I'm assuming (as in Sam Nead's answer) that the covering should be locally isometric. By Ahlfors-Bers, a tame infinite volume hyperbolic manifold with ends of th …
Danny Ruberman's user avatar
12 votes

Harmonic spinors on closed hyperbolic manifolds

I'm happy to be able to answer my own question! John Ratcliffe, Steven Tschantz and I showed that the Dirac operator on the Davis manifold (a closed hyperbolic 4-manifold constructed by Mike Davis) ha …
Danny Ruberman's user avatar
9 votes

When are those subgroups of $\mathrm{SL}(2, \mathbb{C})$ discrete?

If you want to know if your group is not discrete, apply Jorgensen's inequality (Jørgensen, Troels (1976), "On discrete groups of Möbius transformations", American Journal of Mathematics 98 (3): 739–7 …
Danny Ruberman's user avatar
6 votes

Reference for shortest educational path to (Riemannian) hyperbolic plane

Ted Shifrin's course notes on curves and surfaces has a nice introduction to hyperbolic geometry in the plane. You have to refer to the earlier part of the book for the notation related to Riemannian …
Danny Ruberman's user avatar
6 votes

Hyperbolic volume of hyperbolic knots

For question 2, the answer is no. There are plenty of distinct hyperbolic knots (and hence having distinct fundamental group) with the same volume. For example, the Conway and Kinoshita-Terasaka knot …
Danny Ruberman's user avatar
8 votes

Smooth projective varieties with infinite abelian fundamental group and finite $\pi_2$

With regard to surfaces: it is a simple theorem that $\pi_2$ of any closed $4$-manifold is torsion free; so one doesn't need any complex geometry to see that there are no such projective surfaces. Th …
Danny Ruberman's user avatar