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Acknowledged mistake, added something hopefully useful
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HJRW
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As Bruno rightly points out, my first answer (below) is nonsense. So let me try to say something else vaguely useful.

In the Spring, I heard Ian Biringer talk about his recent work with Juan Souto. I'm pretty sure he stated the following theorem:

Theorem: Let $\epsilon>0$ and $r\in\mathbb{N}$. There are finitely many hyperbolic 3-manifolds with boundary $M_1,\ldots,M_k$ with the property that any hyperbolic 3-manifold $M$ with injectivity radius greater than $\epsilon$ and $\mathrm{rank}\pi_1M\leq r$ can be obtained by gluing the $M_i$ together along their boundaries.

This would imply that there is a finite generating set of blocks for hyperbolic manifolds with appropriate restrictions on the injectivity radius and rank. I believe the proof is non-constructive, so one doesn't actually know what the $M_i$ are.

Poking around on the archive and Ian's web page, I don't see the result in question, so I'm at a loss to provide a reference! But if this sounds useful, then no doubt one could contact Ian or Juan and get the details.


I'm somewhat out of my comfort zone here, but I think this is right.

The figure-8 knot complement $M_8$ is universal, meaning that every closed 3-manifold arises as a Dehn filling on a finite-sheeted covering space of $M_8$. So the family $\lbrace M_8, D^2\times S^1\rbrace$ generates all 3-manifolds. So the family $\lbrace M_8, D^2\times S^1\rbrace$ generates all 3-manifolds.

I don't have time to look at the references right now, but I'll try to get back to it later.

I'm somewhat out of my comfort zone here, but I think this is right.

The figure-8 knot complement $M_8$ is universal, meaning that every closed 3-manifold arises as a Dehn filling on a finite-sheeted covering space of $M_8$. So the family $\lbrace M_8, D^2\times S^1\rbrace$ generates all 3-manifolds.

I don't have time to look at the references right now, but I'll try to get back to it later.

As Bruno rightly points out, my first answer (below) is nonsense. So let me try to say something else vaguely useful.

In the Spring, I heard Ian Biringer talk about his recent work with Juan Souto. I'm pretty sure he stated the following theorem:

Theorem: Let $\epsilon>0$ and $r\in\mathbb{N}$. There are finitely many hyperbolic 3-manifolds with boundary $M_1,\ldots,M_k$ with the property that any hyperbolic 3-manifold $M$ with injectivity radius greater than $\epsilon$ and $\mathrm{rank}\pi_1M\leq r$ can be obtained by gluing the $M_i$ together along their boundaries.

This would imply that there is a finite generating set of blocks for hyperbolic manifolds with appropriate restrictions on the injectivity radius and rank. I believe the proof is non-constructive, so one doesn't actually know what the $M_i$ are.

Poking around on the archive and Ian's web page, I don't see the result in question, so I'm at a loss to provide a reference! But if this sounds useful, then no doubt one could contact Ian or Juan and get the details.


I'm somewhat out of my comfort zone here, but I think this is right.

The figure-8 knot complement $M_8$ is universal, meaning that every closed 3-manifold arises as a Dehn filling on a finite-sheeted covering space of $M_8$. So the family $\lbrace M_8, D^2\times S^1\rbrace$ generates all 3-manifolds.

I don't have time to look at the references right now, but I'll try to get back to it later.

Source Link
HJRW
  • 25k
  • 3
  • 68
  • 144

I'm somewhat out of my comfort zone here, but I think this is right.

The figure-8 knot complement $M_8$ is universal, meaning that every closed 3-manifold arises as a Dehn filling on a finite-sheeted covering space of $M_8$. So the family $\lbrace M_8, D^2\times S^1\rbrace$ generates all 3-manifolds.

I don't have time to look at the references right now, but I'll try to get back to it later.