The Link Volume of 3-Manifolds Work in Progress Yoav Rieck - - PowerPoint PPT Presentation

the link volume of 3 manifolds
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The Link Volume of 3-Manifolds Work in Progress Yoav Rieck - - PowerPoint PPT Presentation

The Link Volume of 3-Manifolds Work in Progress Yoav Rieck (University of Arkansas) Yasushi Yamashita (Nara Womens University) December 22, 2010, Nihon Daigaku Background p S 3 , L be a branched cover Let M be a closed, orientable


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SLIDE 1

The Link Volume of 3-Manifolds

Work in Progress

Yo’av Rieck (University of Arkansas) Yasushi Yamashita (Nara Women’s University)

December 22, 2010, Nihon Daigaku

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SLIDE 2

Background

Let M be a closed, orientable 3-manifolds. M

p

→ S3, L be a branched cover with branch set L ⊂ S3 and degree p.

slide-3
SLIDE 3

Background

Let M be a closed, orientable 3-manifolds. M

p

→ S3, L be a branched cover with branch set L ⊂ S3 and degree p.

  • (Alexander) such a cover always exists.
slide-4
SLIDE 4

Background

Let M be a closed, orientable 3-manifolds. M

p

→ S3, L be a branched cover with branch set L ⊂ S3 and degree p.

  • (Alexander) such a cover always exists.
  • (Thurston, Hilden-Lozano-Montesinos) May assume L is a hyperbolic link.
slide-5
SLIDE 5

Background

Let M be a closed, orientable 3-manifolds. M

p

→ S3, L be a branched cover with branch set L ⊂ S3 and degree p.

  • (Alexander) such a cover always exists.
  • (Thurston, Hilden-Lozano-Montesinos) May assume L is a hyperbolic link.
  • Much more is known!
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SLIDE 6

The Link Volume

LinkVol(M) = inf{pVol(S3 \ L)|M

p

→ S3, L hyperbolic}

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SLIDE 7

The Link Volume

LinkVol(M) = inf{pVol(S3 \ L)|M

p

→ S3, L hyperbolic} Basic facts about the Link Volume:

  • The infimum is obtained.
slide-8
SLIDE 8

The Link Volume

LinkVol(M) = inf{pVol(S3 \ L)|M

p

→ S3, L hyperbolic} Basic facts about the Link Volume:

  • The infimum is obtained.
  • There exists

L ⊂ M so that LinkVol(M) = Vol(M \ L).

slide-9
SLIDE 9

The Link Volume

LinkVol(M) = inf{pVol(S3 \ L)|M

p

→ S3, L hyperbolic} Basic facts about the Link Volume:

  • The infimum is obtained.
  • There exists

L ⊂ M so that LinkVol(M) = Vol(M \ L).

  • If M is hyperbolic then Vol(M) < LinkVol(M).
slide-10
SLIDE 10

The Link Volume

LinkVol(M) = inf{pVol(S3 \ L)|M

p

→ S3, L hyperbolic} Basic facts about the Link Volume:

  • The infimum is obtained.
  • There exists

L ⊂ M so that LinkVol(M) = Vol(M \ L).

  • If M is hyperbolic then Vol(M) < LinkVol(M).
  • There are infinitely many M’s with LinkVol(M) < V (for V not too small).
slide-11
SLIDE 11

The Link Volume

LinkVol(M) = inf{pVol(S3 \ L)|M

p

→ S3, L hyperbolic} Basic facts about the Link Volume:

  • The infimum is obtained.
  • There exists

L ⊂ M so that LinkVol(M) = Vol(M \ L).

  • If M is hyperbolic then Vol(M) < LinkVol(M).
  • There are infinitely many M’s with LinkVol(M) < V (for V not too small).

Moreover, in work currently in progress we show: THEOREM (Jair Remigio–Ju´ arez—R): There exist infinitely many man- ifolds with the same link volume.

slide-12
SLIDE 12

A few questions

LinkVol(M) = inf{pVol(S3 \ L)|M

p

→ S3, L hyperbolic }

slide-13
SLIDE 13

A few questions

LinkVol(M) = inf{pVol(S3 \ L)|M

p

→ S3, L hyperbolic } Basic questions about the Link Volume:

  • Calculate LinkVol(M).
slide-14
SLIDE 14

A few questions

LinkVol(M) = inf{pVol(S3 \ L)|M

p

→ S3, L hyperbolic } Basic questions about the Link Volume:

  • Calculate LinkVol(M).
  • Do there exist hyperbolic manifolds M1, M2 with Vol(M1) = Vol(M2) and

LinkVol(M1) = LinkVol(M2)?

slide-15
SLIDE 15

A few questions

LinkVol(M) = inf{pVol(S3 \ L)|M

p

→ S3, L hyperbolic } Basic questions about the Link Volume:

  • Calculate LinkVol(M).
  • Do there exist hyperbolic manifolds M1, M2 with Vol(M1) = Vol(M2) and

LinkVol(M1) = LinkVol(M2)?

  • Do there exist hyperbolic manifolds M1, M2 with LinkVol(M1) = LinkVol(M2)

and Vol(M1) = Vol(M2)

slide-16
SLIDE 16

A few questions

LinkVol(M) = inf{pVol(S3 \ L)|M

p

→ S3, L hyperbolic } Basic questions about the Link Volume:

  • Calculate LinkVol(M).
  • Do there exist hyperbolic manifolds M1, M2 with Vol(M1) = Vol(M2) and

LinkVol(M1) = LinkVol(M2)?

  • Do there exist hyperbolic manifolds M1, M2 with LinkVol(M1) = LinkVol(M2)

and Vol(M1) = Vol(M2)

  • What is the degree of the cover that realizes LinkVol(M)? What does it

say about M?

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SLIDE 17

Theorem 1

Let X be a compact manifold, ∂X tori. Suppose that slopes (mi, li) were chosen

  • n each component of ∂X (|mi ∩ li| = 1).
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SLIDE 18

Theorem 1

Let X be a compact manifold, ∂X tori. Suppose that slopes (mi, li) were chosen

  • n each component of ∂X (|mi ∩ li| = 1).

Any slope αi can be written as a rational number. The depth pf αi is the length

  • f its shortest partial fraction expansion.
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SLIDE 19

Theorem 1

Let X be a compact manifold, ∂X tori. Suppose that slopes (mi, li) were chosen

  • n each component of ∂X (|mi ∩ li| = 1).

Any slope αi can be written as a rational number. The depth pf αi is the length

  • f its shortest partial fraction expansion.

If α = (α1, . . . , αk) is a multislope (ie, one slope on each component of ∂X) we define depth(α) = Σidepth(αi).

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SLIDE 20

Theorem 1

Let X be a compact manifold, ∂X tori. Suppose that slopes (mi, li) were chosen

  • n each component of ∂X (|mi ∩ li| = 1).

Any slope αi can be written as a rational number. The depth pf αi is the length

  • f its shortest partial fraction expansion.

If α = (α1, . . . , αk) is a multislope (ie, one slope on each component of ∂X) we define depth(α) = Σidepth(αi). We denote the manifold obtained by filling ∂X along the slopes α by X(α).

slide-21
SLIDE 21

Theorem 1

Let X be a compact manifold, ∂X tori. Suppose that slopes (mi, li) were chosen

  • n each component of ∂X (|mi ∩ li| = 1).

Any slope αi can be written as a rational number. The depth pf αi is the length

  • f its shortest partial fraction expansion.

If α = (α1, . . . , αk) is a multislope (ie, one slope on each component of ∂X) we define depth(α) = Σidepth(αi). We denote the manifold obtained by filling ∂X along the slopes α by X(α). THEOREM 1. Let X be as above. Then there exist a, b, so that: LinkVol(X(α)) < adepth(α) + b.

slide-22
SLIDE 22

Theorem 1

Let X be a compact manifold, ∂X tori. Suppose that slopes (mi, li) were chosen

  • n each component of ∂X (|mi ∩ li| = 1).

Any slope αi can be written as a rational number. The depth pf αi is the length

  • f its shortest partial fraction expansion.

If α = (α1, . . . , αk) is a multislope (ie, one slope on each component of ∂X) we define depth(α) = Σidepth(αi). We denote the manifold obtained by filling ∂X along the slopes α by X(α). THEOREM 1. Let X be as above. Then there exist a, b, so that: LinkVol(X(α)) < adepth(α) + b. Remark: a is independent of X.

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SLIDE 23

Theorem 2

For any V > 0, let MV = {M|LinkVol(M) < V }. Jørgensen—Thurston gives:

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SLIDE 24

Theorem 2

For any V > 0, let MV = {M|LinkVol(M) < V }. Jørgensen—Thurston gives: THEOREM 2. There exist K, so that for any V and any M ∈ MV , there are hyperbolic manifolds X, E, and an unbranched cover X → E, so that the following diagram commutes (horizontal arrows represent Dehn fillings): E X ❄ ✲ S3, L ❄ M ✲

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SLIDE 25

Theorem 2

For any V > 0, let MV = {M|LinkVol(M) < V }. Jørgensen—Thurston gives: THEOREM 2. There exist K, so that for any V and any M ∈ MV , there are hyperbolic manifolds X, E, and an unbranched cover X → E, so that the following diagram commutes (horizontal arrows represent Dehn fillings): E X ❄ ✲ S3, L ❄ M ✲ and E admits a triangulation with ≤ K

d V tetrahedra, where d are the degrees

  • f the covers above. Hence X admits an invariant triangulation with ≤ KV
  • tetrahedra. Note: Vol(X) < cV , for some c.
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SLIDE 26

LinkVol >> Vol

This suggests the following conjecture:

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SLIDE 27

LinkVol >> Vol

This suggests the following conjecture:

  • CONJECTURE. LinkVol >> Vol.
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SLIDE 28

LinkVol >> Vol

This suggests the following conjecture:

  • CONJECTURE. LinkVol >> Vol.

What could this mean:

  • 1. LinkVol(M) − Vol(M) is unbounded
slide-29
SLIDE 29

LinkVol >> Vol

This suggests the following conjecture:

  • CONJECTURE. LinkVol >> Vol.

What could this mean:

  • 1. LinkVol(M) − Vol(M) is unbounded
  • 2. Stronger: LinkVol(M)/Vol(M) is unbounded
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SLIDE 30

LinkVol >> Vol

This suggests the following conjecture:

  • CONJECTURE. LinkVol >> Vol.

What could this mean:

  • 1. LinkVol(M) − Vol(M) is unbounded
  • 2. Stronger: LinkVol(M)/Vol(M) is unbounded
  • 3. Stronger still: there exists hyperbolic manifolds with bounded volumes and

unbounded link volumes.

slide-31
SLIDE 31

LinkVol >> Vol

This suggests the following conjecture:

  • CONJECTURE. LinkVol >> Vol.

What could this mean:

  • 1. LinkVol(M) − Vol(M) is unbounded
  • 2. Stronger: LinkVol(M)/Vol(M) is unbounded
  • 3. Stronger still: there exists hyperbolic manifolds with bounded volumes and

unbounded link volumes. None of these is known in the current time.

slide-32
SLIDE 32

LinkVol >> Vol

This suggests the following conjecture:

  • CONJECTURE. LinkVol >> Vol.

What could this mean:

  • 1. LinkVol(M) − Vol(M) is unbounded
  • 2. Stronger: LinkVol(M)/Vol(M) is unbounded
  • 3. Stronger still: there exists hyperbolic manifolds with bounded volumes and

unbounded link volumes. None of these is known in the current time. If LinkVol(M)/Vol(M) is bounded, we get a very interesting consequence.

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SLIDE 33

That’s it!

THANK YOU VERY MUCH.

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SLIDE 34

LinkVol >> Vol

This suggests the following conjecture:

  • CONJECTURE. LinkVol >> Vol.

What could this mean:

  • 1. LinkVol(M) − Vol(M) is unbounded
  • 2. Stronger: LinkVol(M)/Vol(M) is unbounded
  • 3. Stronger still: there exists hyperbolic manifolds with bounded volumes and

unbounded link volumes. None of these is known in the current time. If LinkVol(M)/Vol(M) is bounded, we get a very interesting consequence.

slide-35
SLIDE 35

Theorem 2

For any V > 0, let MV = {M|LinkVol(M) < V }. Jørgensen—Thurston gives: THEOREM 2. There exist K, so that for any V and any M ∈ MV , there are hyperbolic manifolds X, E, and an unbranched cover X → E, so that the following diagram commutes (horizontal arrows represent Dehn fillings): E X ❄ ✲ S3, L ❄ M ✲ and E admits a triangulation with ≤ K

d V tetrahedra, where d are the degrees

  • f the covers above. Hence X admits an invariant triangulation with ≤ KV
  • tetrahedra. Note: Vol(X) < cV , for some c.
slide-36
SLIDE 36

Theorem 1

Let X be a compact manifold, ∂X tori. Suppose that slopes (mi, li) were chosen

  • n each component of ∂X (|mi ∩ li| = 1).

Any slope αi can be written as a rational number. The depth pf αi is the length

  • f its shortest partial fraction expansion.

If α = (α1, . . . , αk) is a multislope (ie, one slope on each component of ∂X) we define depth(α) = Σidepth(αi). We denote the manifold obtained by filling ∂X along the slopes α by X(α). THEOREM 1. Let X be as above. Then there exist a, b, so that: LinkVol(X(α)) < adepth(α) + b. Remark: a is independent of X.

slide-37
SLIDE 37

A few questions

LinkVol(M) = inf{pVol(S3 \ L)|M

p

→ S3, L hyperbolic } Basic questions about the Link Volume:

  • Calculate LinkVol(M).
  • Do there exist hyperbolic manifolds M1, M2 with Vol(M1) = Vol(M2) and

LinkVol(M1) = LinkVol(M2)?

  • Do there exist hyperbolic manifolds M1, M2 with LinkVol(M1) = LinkVol(M2)

and Vol(M1) = Vol(M2)

  • What is the degree of the cover that realizes LinkVol(M)? What does it

say about M?

slide-38
SLIDE 38

The Link Volume

LinkVol(M) = inf{pVol(S3 \ L)|M

p

→ S3, L hyperbolic} Basic facts about the Link Volume:

  • The infimum is obtained.
  • There exists

L ⊂ M so that LinkVol(M) = Vol(M \ L).

  • If M is hyperbolic then Vol(M) < LinkVol(M).
  • There are infinitely many M’s with LinkVol(M) < V (for V not too small).

Moreover, in work currently in progress we show: THEOREM (Jair Remigio–Ju´ arez—R): There exist infinitely many man- ifolds with the same link volume.

slide-39
SLIDE 39

The Link Volume of 3-Manifolds

Work in Progress

Yo’av Rieck (University of Arkansas) Yasushi Yamashita (Nara Women’s University)

December 22, 2010, Nihon Daigaku

slide-40
SLIDE 40

Background

Let M be a closed, orientable 3-manifolds. M

p

→ S3, L be a branched cover with branch set L ⊂ S3 and degree p.

slide-41
SLIDE 41

Background

Let M be a closed, orientable 3-manifolds. M

p

→ S3, L be a branched cover with branch set L ⊂ S3 and degree p.

  • (Alexander) such a cover always exists.
slide-42
SLIDE 42

Background

Let M be a closed, orientable 3-manifolds. M

p

→ S3, L be a branched cover with branch set L ⊂ S3 and degree p.

  • (Alexander) such a cover always exists.
  • (Thurston, Hilden-Lozano-Montesinos) May assume L is a hyperbolic link.
slide-43
SLIDE 43

Background

Let M be a closed, orientable 3-manifolds. M

p

→ S3, L be a branched cover with branch set L ⊂ S3 and degree p.

  • (Alexander) such a cover always exists.
  • (Thurston, Hilden-Lozano-Montesinos) May assume L is a hyperbolic link.
  • Much more is known!