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An Introduction to the and its generalizations, I

Hitoshi Murakami

Tohoku University

Workshop on Volume Conjecture and Related Topics in Theory Indian Institute of Science Education and Research, Pune 19th December, 2018

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 1 / 23 Outline

1 colored

2 Examples of the colored Jones polynomials

3 Volume conjecture

4 Volume conjecture for the figure-eight knot

5 VC is proved for ...

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 2 / 23 ⟨ ⟩ Kauffman⟨ ⟩ bracket⟨ D⟩ for a knot⟨ diagram⟩ D is defined as = A + A−1 , ⟨ ⟩ ⊔ D = (−A2 − A−2)⟨D⟩, ⟨ ⟩ = 1.

Here ⊔⟨denotes the disjoint union.⟩ Note: ⊔ ⊔ · · · ⊔ = (−A2 − A−2)c−1. | {z } c

colored Jones polynomial Kauffman bracket

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 3 / 23 ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A + A−1 , ⟨ ⟩ ⊔ D = (−A2 − A−2)⟨D⟩, ⟨ ⟩ = 1.

Here ⊔⟨denotes the disjoint union.⟩ Note: ⊔ ⊔ · · · ⊔ = (−A2 − A−2)c−1. | {z } c

colored Jones polynomial Kauffman bracket

Kauffman bracket ⟨D⟩ for a knot diagram D is defined as

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 3 / 23 ⟨ ⟩ Note: ⊔ ⊔ · · · ⊔ = (−A2 − A−2)c−1. | {z } c

colored Jones polynomial Kauffman bracket

⟨ ⟩ Kauffman⟨ ⟩ bracket⟨ D⟩ for a knot⟨ diagram⟩ D is defined as = A + A−1 , ⟨ ⟩ ⊔ D = (−A2 − A−2)⟨D⟩, ⟨ ⟩ = 1.

Here ⊔ denotes the disjoint union.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 3 / 23 colored Jones polynomial Kauffman bracket

⟨ ⟩ Kauffman⟨ ⟩ bracket⟨ D⟩ for a knot⟨ diagram⟩ D is defined as = A + A−1 , ⟨ ⟩ ⊔ D = (−A2 − A−2)⟨D⟩, ⟨ ⟩ = 1.

Here ⊔⟨denotes the disjoint union.⟩ Note: ⊔ ⊔ · · · ⊔ = (−A2 − A−2)c−1. | {z } c

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 3 / 23 ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A + A−1

⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A2 + + + A−2

⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A3 + A + A + A−1

⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ +A + A−1 + A−1 + A−3 .

= A3(−A2 − A−2)2 + A(−A2 − A−2) + A(−A2 − A−2) + A−1 +A(−A2 − A−2) + A−1 + A−1 + A−3(−A2 − A−2) = A7 − A3 − A−5.

colored Jones polynomial Kauffman bracket of the trefoil

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 4 / 23 ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A2 + + + A−2

⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A3 + A + A + A−1

⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ +A + A−1 + A−1 + A−3 .

= A3(−A2 − A−2)2 + A(−A2 − A−2) + A(−A2 − A−2) + A−1 +A(−A2 − A−2) + A−1 + A−1 + A−3(−A2 − A−2) = A7 − A3 − A−5.

colored Jones polynomial Kauffman bracket of the trefoil ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A + A−1

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 4 / 23 ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A3 + A + A + A−1

⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ +A + A−1 + A−1 + A−3 .

= A3(−A2 − A−2)2 + A(−A2 − A−2) + A(−A2 − A−2) + A−1 +A(−A2 − A−2) + A−1 + A−1 + A−3(−A2 − A−2) = A7 − A3 − A−5.

colored Jones polynomial Kauffman bracket of the trefoil ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A + A−1

⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A2 + + + A−2

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 4 / 23 = A3(−A2 − A−2)2 + A(−A2 − A−2) + A(−A2 − A−2) + A−1 +A(−A2 − A−2) + A−1 + A−1 + A−3(−A2 − A−2) = A7 − A3 − A−5.

colored Jones polynomial Kauffman bracket of the trefoil ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A + A−1

⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A2 + + + A−2

⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A3 + A + A + A−1

⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ +A + A−1 + A−1 + A−3 .

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 4 / 23 = A7 − A3 − A−5.

colored Jones polynomial Kauffman bracket of the trefoil ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A + A−1

⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A2 + + + A−2

⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A3 + A + A + A−1

⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ +A + A−1 + A−1 + A−3 .

= A3(−A2 − A−2)2 + A(−A2 − A−2) + A(−A2 − A−2) + A−1 +A(−A2 − A−2) + A−1 + A−1 + A−3(−A2 − A−2)

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 4 / 23 colored Jones polynomial Kauffman bracket of the trefoil ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A + A−1

⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A2 + + + A−2

⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ = A3 + A + A + A−1

⟨ ⟩ ⟨ ⟩ ⟨ ⟩ ⟨ ⟩ +A + A−1 + A−1 + A−3 .

= A3(−A2 − A−2)2 + A(−A2 − A−2) + A(−A2 − A−2) + A−1 +A(−A2 − A−2) + A−1 + A−1 + A−3(−A2 − A−2) = A7 − A3 − A−5.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 4 / 23 Definition () D⃗ : oriented knot diagram. • w(D⃗ ) := ♯ − ♯

Definition K: oriented knot presented by D⃗ . ⃗ D: D without orientation. ⃗ V (K; q) := (−A3)−w(D)⟨D⟩ . q:=A−4

V (K; q) is a , called the Jones polynomial.

colored Jones polynomial Jones polynomial

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 5 / 23 Definition K: oriented knot presented by D⃗ . ⃗ D: D without orientation. ⃗ V (K; q) := (−A3)−w(D)⟨D⟩ . q:=A−4

V (K; q) is a knot invariant, called the Jones polynomial.

colored Jones polynomial Jones polynomial

Definition (writhe) D⃗ : oriented knot diagram. • w(D⃗ ) := ♯ − ♯

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 5 / 23 K: oriented knot presented by D⃗ . ⃗ D: D without orientation. ⃗ V (K; q) := (−A3)−w(D)⟨D⟩ . q:=A−4

V (K; q) is a knot invariant, called the Jones polynomial.

colored Jones polynomial Jones polynomial

Definition (writhe) D⃗ : oriented knot diagram. • w(D⃗ ) := ♯ − ♯

Definition

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 5 / 23 colored Jones polynomial Jones polynomial

Definition (writhe) D⃗ : oriented knot diagram. • w(D⃗ ) := ♯ − ♯

Definition K: oriented knot presented by D⃗ . ⃗ D: D without orientation. ⃗ V (K; q) := (−A3)−w(D)⟨D⟩ . q:=A−4

V (K; q) is a knot invariant, called the Jones polynomial.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 5 / 23     w   = −3  

  ⇒ J  ; q = −A9(A7 − A3 − A−5) = −q−4 + q−3 + q−1. q:=A−4       − − J  ; q = q2 − q + 1 − q 1 − q 2.

colored Jones polynomial Example of the Jones polynomials

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 6 / 23  

  ⇒ J  ; q = −A9(A7 − A3 − A−5) = −q−4 + q−3 + q−1. q:=A−4       − − J  ; q = q2 − q + 1 − q 1 − q 2.

colored Jones polynomial Example of the Jones polynomials

    w   = −3

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 6 / 23       − − J  ; q = q2 − q + 1 − q 1 − q 2.

colored Jones polynomial Example of the Jones polynomials

    w   = −3  

  ⇒ J  ; q = −A9(A7 − A3 − A−5) = −q−4 + q−3 + q−1. q:=A−4

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 6 / 23 colored Jones polynomial Example of the Jones polynomials

    w   = −3  

  ⇒ J  ; q = −A9(A7 − A3 − A−5) = −q−4 + q−3 + q−1. q:=A−4       − − J  ; q = q2 − q + 1 − q 1 − q 2.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 6 / 23 2 • 2 − 1 ⇒ := (−A2−A2) =

Definition (Jones–Wenzl idempotent)

k−1 ( ) 1 k k−1 ∆k−2 := 1 − k−2 ∆k−1 1 k−1 ⟨ ⟩ − − k A2(k+1)−A 2(k+1) k with ∆k := ( 1) A2−A−2 = .

k ⇒ = , = (−1)k Ak2+2k k

colored Jones polynomial Jones–Wenzl idempotent

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 7 / 23 2 ⇒ =

Definition (Jones–Wenzl idempotent)

k−1 ( ) 1 k k−1 ∆k−2 := 1 − k−2 ∆k−1 1 k−1 ⟨ ⟩ − − k A2(k+1)−A 2(k+1) k with ∆k := ( 1) A2−A−2 = .

k ⇒ = , = (−1)k Ak2+2k k

colored Jones polynomial Jones–Wenzl idempotent

• 2 − 1 := (−A2−A2)

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 7 / 23 Definition (Jones–Wenzl idempotent)

k−1 ( ) 1 k k−1 ∆k−2 := 1 − k−2 ∆k−1 1 k−1 ⟨ ⟩ − − k A2(k+1)−A 2(k+1) k with ∆k := ( 1) A2−A−2 = .

k ⇒ = , = (−1)k Ak2+2k k

colored Jones polynomial Jones–Wenzl idempotent 2 • 2 − 1 ⇒ := (−A2−A2) =

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 7 / 23 k ⇒ = , = (−1)k Ak2+2k k

colored Jones polynomial Jones–Wenzl idempotent 2 • 2 − 1 ⇒ := (−A2−A2) =

Definition (Jones–Wenzl idempotent)

k−1 ( ) 1 k k−1 ∆k−2 := 1 − k−2 ∆k−1 1 k−1 ⟨ ⟩ − − k A2(k+1)−A 2(k+1) k with ∆k := ( 1) A2−A−2 = .

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 7 / 23 = (−1)k Ak2+2k k

colored Jones polynomial Jones–Wenzl idempotent 2 • 2 − 1 ⇒ := (−A2−A2) =

Definition (Jones–Wenzl idempotent)

k−1 ( ) 1 k k−1 ∆k−2 := 1 − k−2 ∆k−1 1 k−1 ⟨ ⟩ − − k A2(k+1)−A 2(k+1) k with ∆k := ( 1) A2−A−2 = .

k ⇒ = ,

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 7 / 23 colored Jones polynomial Jones–Wenzl idempotent 2 • 2 − 1 ⇒ := (−A2−A2) =

Definition (Jones–Wenzl idempotent)

k−1 ( ) 1 k k−1 ∆k−2 := 1 − k−2 ∆k−1 1 k−1 ⟨ ⟩ − − k A2(k+1)−A 2(k+1) k with ∆k := ( 1) A2−A−2 = .

k ⇒ = , = (−1)k Ak2+2k k

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 7 / 23 D : knot diagram.

k ⇒ D : diagram obtained from D by replacing the string with the

Jones–Wenzl idempotent Definition (N-colored Jones polynomial) ⟨ ⟩ ( ) −w(D⃗ ) − N−1 N2−1 N−1 JN (K; q) := ( 1) A D . q:=A4

−1 J2(K; q) = V (K; q ).

colored Jones polynomial colored Jones polynomial

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 8 / 23 k ⇒ D : diagram obtained from D by replacing the string with the

Jones–Wenzl idempotent Definition (N-colored Jones polynomial) ⟨ ⟩ ( ) −w(D⃗ ) − N−1 N2−1 N−1 JN (K; q) := ( 1) A D . q:=A4

−1 J2(K; q) = V (K; q ).

colored Jones polynomial colored Jones polynomial

D : knot diagram.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 8 / 23 Definition (N-colored Jones polynomial) ⟨ ⟩ ( ) −w(D⃗ ) − N−1 N2−1 N−1 JN (K; q) := ( 1) A D . q:=A4

−1 J2(K; q) = V (K; q ).

colored Jones polynomial colored Jones polynomial

D : knot diagram.

k ⇒ D : diagram obtained from D by replacing the string with the

Jones–Wenzl idempotent

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 8 / 23 −1 J2(K; q) = V (K; q ).

colored Jones polynomial colored Jones polynomial

D : knot diagram.

k ⇒ D : diagram obtained from D by replacing the string with the

Jones–Wenzl idempotent Definition (N-colored Jones polynomial) ⟨ ⟩ ( ) −w(D⃗ ) − N−1 N2−1 N−1 JN (K; q) := ( 1) A D . q:=A4

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 8 / 23 colored Jones polynomial colored Jones polynomial

D : knot diagram.

k ⇒ D : diagram obtained from D by replacing the string with the

Jones–Wenzl idempotent Definition (N-colored Jones polynomial) ⟨ ⟩ ( ) −w(D⃗ ) − N−1 N2−1 N−1 JN (K; q) := ( 1) A D . q:=A4

−1 J2(K; q) = V (K; q ). Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 8 / 23 1 3 4 J2( ; q) =q + q − q , 2 5 7 8 9 10 11 J3( ; q) =q + q − q + q − q − q + q , 3 7 10 11 13 14 15 17 19 J4( ; q) =q + q − q + q − q − q + q − q + q + q20 − q21 . . (−1)N−1q3(N2−1)/2 J ( ; q) = N qN/2 − q−N/2 N∑−1 2 × (−1)k q−3(k +k)/2(q(2k+1)/2 − q−(2k+1)/2). k=0 (M. Rosso, V. Jones, H. Morton)

Examples of the colored Jones polynomials colored Jones polynomials of

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 9 / 23 Examples of the colored Jones polynomials colored Jones polynomials of

1 3 4 J2( ; q) =q + q − q , 2 5 7 8 9 10 11 J3( ; q) =q + q − q + q − q − q + q , 3 7 10 11 13 14 15 17 19 J4( ; q) =q + q − q + q − q − q + q − q + q + q20 − q21 . . (−1)N−1q3(N2−1)/2 J ( ; q) = N qN/2 − q−N/2 N∑−1 2 × (−1)k q−3(k +k)/2(q(2k+1)/2 − q−(2k+1)/2). k=0 (M. Rosso, V. Jones, H. Morton)

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 9 / 23 2 −1 −2 J2( ) =q − q + 1 − q + q , 6 5 4 3 2 −1 −2 −3 −4 J3( ) =q − q − q + 2q − q − q + 3 − q − q + 2q − q − q−5 + q−6,

12 11 10 8 6 4 2 −2 −4 J4( ) =q − q − q + 2q − 2q + 3q − 3q + 3 − 3q + 3q − 2q−6 + 2q−8 − q−10 − q−11 + q−12 . . N∑−1 ∏j ( )( ) (N−k)/2 −(N−k)/2 (N+k)/2 −(N+k)/2 JN ( ; q) = q − q q − q . j=0 k=1

(K. Habiro, T. Lˆe)

Examples of the colored Jones polynomials colored Jones polynomials of

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 10 / 23 Examples of the colored Jones polynomials colored Jones polynomials of

2 −1 −2 J2( ) =q − q + 1 − q + q , 6 5 4 3 2 −1 −2 −3 −4 J3( ) =q − q − q + 2q − q − q + 3 − q − q + 2q − q − q−5 + q−6,

12 11 10 8 6 4 2 −2 −4 J4( ) =q − q − q + 2q − 2q + 3q − 3q + 3 − 3q + 3q − 2q−6 + 2q−8 − q−10 − q−11 + q−12 . . N∑−1 ∏j ( )( ) (N−k)/2 −(N−k)/2 (N+k)/2 −(N+k)/2 JN ( ; q) = q − q q − q . j=0 k=1

(K. Habiro, T. Lˆe)

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 10 / 23 ( √ ) ( √ ) 1 | − | |JN ; exp(2π −1/N) | N log JN ; exp(2π 1/N) 0.6 1000

0.5 800

0.4

600 0.3

400 0.2

200 0.1

20 40 60 80 100 20 40 60 80 100 JN ( ; q) N−1 3(N2−1)/2 N∑−1 (−1) q 2 = (−1)k q−3(k +k)/2(q(2k+1)/2 − q−(2k+1)/2) qN/2 − q−N/2 k=0

Examples of the colored Jones polynomials Colored Jones polynomial at Nth root of unity,

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 11 / 23 ( √ ) 1 | − | N log JN ; exp(2π 1/N) 0.6

0.5

0.4

0.3

0.2

0.1

20 40 60 80 100 JN ( ; q) N−1 3(N2−1)/2 N∑−1 (−1) q 2 = (−1)k q−3(k +k)/2(q(2k+1)/2 − q−(2k+1)/2) qN/2 − q−N/2 k=0

Examples of the colored Jones polynomials Colored Jones polynomial at Nth root of unity,

( √ ) |JN ; exp(2π −1/N) |

1000

800

600

400

200

20 40 60 80 100

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 11 / 23 Examples of the colored Jones polynomials Colored Jones polynomial at Nth root of unity,

( √ ) ( √ ) 1 | − | |JN ; exp(2π −1/N) | N log JN ; exp(2π 1/N) 0.6 1000

0.5 800

0.4

600 0.3

400 0.2

200 0.1

20 40 60 80 100 20 40 60 80 100 JN ( ; q) N−1 3(N2−1)/2 N∑−1 (−1) q 2 = (−1)k q−3(k +k)/2(q(2k+1)/2 − q−(2k+1)/2) qN/2 − q−N/2 k=0

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 11 / 23 Graph of ( Graph of√ ) ( √ ) 1 | − | |JN ; exp(2π −1/N) |. N log JN ; exp(2π 1/N) .

0.8 6 × 1014

5 × 1014 0.6 4 × 1014

3 × 1014 0.4

2 × 1014 0.2 1 × 1014

20 40 60 80 100 20 40 60 80 100 JN∑( ; q∏) ( )( ) N−1 j (N−k)/2 − −(N−k)/2 (N+k)/2 − −(N+k)/2 = j=0 k=1 q q q q . What is the difference between and ?

Examples of the colored Jones polynomials Colored Jones polynomial at Nth root of unity,

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 12 / 23 ( Graph of √ ) 1 | − | N log JN ; exp(2π 1/N) .

0.8

0.6

0.4

0.2

20 40 60 80 100 JN∑( ; q∏) ( )( ) N−1 j (N−k)/2 − −(N−k)/2 (N+k)/2 − −(N+k)/2 = j=0 k=1 q q q q . What is the difference between and ?

Examples of the colored Jones polynomials Colored Jones polynomial at Nth root of unity,

( Graph of√ ) |JN ; exp(2π −1/N) |.

6 × 1014

5 × 1014

4 × 1014

3 × 1014

2 × 1014

1 × 1014

20 40 60 80 100

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 12 / 23 What is the difference between and ?

Examples of the colored Jones polynomials Colored Jones polynomial at Nth root of unity,

Graph of ( Graph of√ ) ( √ ) 1 | − | |JN ; exp(2π −1/N) |. N log JN ; exp(2π 1/N) .

0.8 6 × 1014

5 × 1014 0.6 4 × 1014

3 × 1014 0.4

2 × 1014 0.2 1 × 1014

20 40 60 80 100 20 40 60 80 100 JN∑( ; q∏) ( )( ) N−1 j (N−k)/2 − −(N−k)/2 (N+k)/2 − −(N+k)/2 = j=0 k=1 q q q q .

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 12 / 23 Examples of the colored Jones polynomials Colored Jones polynomial at Nth root of unity,

Graph of ( Graph of√ ) ( √ ) 1 | − | |JN ; exp(2π −1/N) |. N log JN ; exp(2π 1/N) .

0.8 6 × 1014

5 × 1014 0.6 4 × 1014

3 × 1014 0.4

2 × 1014 0.2 1 × 1014

20 40 60 80 100 20 40 60 80 100 JN∑( ; q∏) ( )( ) N−1 j (N−k)/2 − −(N−k)/2 (N+k)/2 − −(N+k)/2 = j=0 k=1 q q q q . What is the difference between and ?

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 12 / 23 Definition (Simplicial volume (Gromov norm)) ∑ 3 Vol(S \ K) := Hyperbolic Volume of Hi .

Hi :hyperbolic piece

Definition (Jaco–Shalen–Johannson decomposition) S3 \ K can be uniquely decomposed as (⊔ ) (⊔ ) 3 S \ K = Hi ⊔ Ej

with Hi hyperbolic and Ej Seifert-fibered.

Volume conjecture Volume conjecture Conjecture (Volume Conjecture, R. Kashaev (1997), J. Murakami+H.M. (2001)) K: knot √ log |J (K; exp(2π −1/N))| 2π lim N = Vol(S3 \ K). N→∞ N

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 13 / 23 Definition (Jaco–Shalen–Johannson decomposition) S3 \ K can be uniquely decomposed as (⊔ ) (⊔ ) 3 S \ K = Hi ⊔ Ej

with Hi hyperbolic and Ej Seifert-fibered.

Volume conjecture Volume conjecture Conjecture (Volume Conjecture, R. Kashaev (1997), J. Murakami+H.M. (2001)) K: knot √ log |J (K; exp(2π −1/N))| 2π lim N = Vol(S3 \ K). N→∞ N

Definition (Simplicial volume (Gromov norm)) ∑ 3 Vol(S \ K) := Hyperbolic Volume of Hi .

Hi :hyperbolic piece

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 13 / 23 Volume conjecture Volume conjecture Conjecture (Volume Conjecture, R. Kashaev (1997), J. Murakami+H.M. (2001)) K: knot √ log |J (K; exp(2π −1/N))| 2π lim N = Vol(S3 \ K). N→∞ N

Definition (Simplicial volume (Gromov norm)) ∑ 3 Vol(S \ K) := Hyperbolic Volume of Hi .

Hi :hyperbolic piece

Definition (Jaco–Shalen–Johannson decomposition) S3 \ K can be uniquely decomposed as (⊔ ) (⊔ ) 3 S \ K = Hi ⊔ Ej with Hi hyperbolic and Ej Seifert-fibered.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 13 / 23 = ⊔ .

hyperbolic Seifert fibered             Vol   = Vol  

Volume conjecture Example of JSJ decomposition

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 14 / 23 hyperbolic Seifert fibered             Vol   = Vol  

Volume conjecture Example of JSJ decomposition

= ⊔ .

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 14 / 23 Seifert fibered             Vol   = Vol  

Volume conjecture Example of JSJ decomposition

= ⊔ .

hyperbolic

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 14 / 23             Vol   = Vol  

Volume conjecture Example of JSJ decomposition

= ⊔ .

hyperbolic Seifert fibered

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 14 / 23 Volume conjecture Example of JSJ decomposition

= ⊔ .

hyperbolic Seifert fibered             Vol   = Vol  

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 14 / 23 Theorem (K. Habiro, T. Lˆe) ( ) N∑−1 ∏j ( )( ) (N−k)/2 −(N−k)/2 (N+k)/2 −(N+k)/2 JN ; q = q − q q − q . j=0 k=1 √ q 7→ exp(2π −1/N)

( √ ) N∑−1 ∏j JN ; exp(2π −1/N) = f (N; k) j=0 k=1

with f (N; k) := 4 sin2(kπ/N).

Volume conjecture for the figure-eight knot Colored Jones polynomial of

Proof of the VC for is given by T. Ekholm in 1999.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 15 / 23 √ q 7→ exp(2π −1/N)

( √ ) N∑−1 ∏j JN ; exp(2π −1/N) = f (N; k) j=0 k=1

with f (N; k) := 4 sin2(kπ/N).

Volume conjecture for the figure-eight knot Colored Jones polynomial of

Proof of the VC for is given by T. Ekholm in 1999. Theorem (K. Habiro, T. Lˆe) ( ) N∑−1 ∏j ( )( ) (N−k)/2 −(N−k)/2 (N+k)/2 −(N+k)/2 JN ; q = q − q q − q . j=0 k=1

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 15 / 23 Volume conjecture for the figure-eight knot Colored Jones polynomial of

Proof of the VC for is given by T. Ekholm in 1999. Theorem (K. Habiro, T. Lˆe) ( ) N∑−1 ∏j ( )( ) (N−k)/2 −(N−k)/2 (N+k)/2 −(N+k)/2 JN ; q = q − q q − q . j=0 k=1 √ q 7→ exp(2π −1/N)

( √ ) N∑−1 ∏j JN ; exp(2π −1/N) = f (N; k) j=0 k=1

with f (N; k) := 4 sin2(kπ/N).

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 15 / 23 ( √ ) N∑−1 ∏j 2π −1/N 2 JN ; e = f (N; k) with f (N; k) := 4 sin (kπ/N). j=0 k=1 Graph of f (N; k) f(N;k)

4

1

0 j N/6 5N/6 ∏ j Put g(N; j) := k=1 f (N; k). j 0 ··· N/6 ··· 5N/6 ··· 1 f (N; k) < 1 1 > 1 1 < 1 g(N; j) 1 ↘ ↗ maximum ↘

Volume conjecture for the figure-eight knot Find the maximum of the summands

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 16 / 23 Graph of f (N; k) f(N;k)

4

1

0 j N/6 5N/6 ∏ j Put g(N; j) := k=1 f (N; k). j 0 ··· N/6 ··· 5N/6 ··· 1 f (N; k) < 1 1 > 1 1 < 1 g(N; j) 1 ↘ ↗ maximum ↘

Volume conjecture for the figure-eight knot Find the maximum of the summands ( √ ) N∑−1 ∏j 2π −1/N 2 JN ; e = f (N; k) with f (N; k) := 4 sin (kπ/N). j=0 k=1

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 16 / 23 ∏ j Put g(N; j) := k=1 f (N; k). j 0 ··· N/6 ··· 5N/6 ··· 1 f (N; k) < 1 1 > 1 1 < 1 g(N; j) 1 ↘ ↗ maximum ↘

Volume conjecture for the figure-eight knot Find the maximum of the summands ( √ ) N∑−1 ∏j 2π −1/N 2 JN ; e = f (N; k) with f (N; k) := 4 sin (kπ/N). j=0 k=1 Graph of f (N; k) f(N;k)

4

1

0 j N/6 5N/6

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 16 / 23 j 0 ··· N/6 ··· 5N/6 ··· 1 f (N; k) < 1 1 > 1 1 < 1 g(N; j) 1 ↘ ↗ maximum ↘

Volume conjecture for the figure-eight knot Find the maximum of the summands ( √ ) N∑−1 ∏j 2π −1/N 2 JN ; e = f (N; k) with f (N; k) := 4 sin (kπ/N). j=0 k=1 Graph of f (N; k) f(N;k)

4

1

0 j N/6 5N/6 ∏ j Put g(N; j) := k=1 f (N; k).

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 16 / 23 f (N; k) < 1 1 > 1 1 < 1 g(N; j) 1 ↘ ↗ maximum ↘

Volume conjecture for the figure-eight knot Find the maximum of the summands ( √ ) N∑−1 ∏j 2π −1/N 2 JN ; e = f (N; k) with f (N; k) := 4 sin (kπ/N). j=0 k=1 Graph of f (N; k) f(N;k)

4

1

0 j N/6 5N/6 ∏ j Put g(N; j) := k=1 f (N; k). j 0 ··· N/6 ··· 5N/6 ··· 1

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 16 / 23 g(N; j) 1 ↘ ↗ maximum ↘

Volume conjecture for the figure-eight knot Find the maximum of the summands ( √ ) N∑−1 ∏j 2π −1/N 2 JN ; e = f (N; k) with f (N; k) := 4 sin (kπ/N). j=0 k=1 Graph of f (N; k) f(N;k)

4

1

0 j N/6 5N/6 ∏ j Put g(N; j) := k=1 f (N; k). j 0 ··· N/6 ··· 5N/6 ··· 1 f (N; k) < 1 1 > 1 1 < 1

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 16 / 23 Volume conjecture for the figure-eight knot Find the maximum of the summands ( √ ) N∑−1 ∏j 2π −1/N 2 JN ; e = f (N; k) with f (N; k) := 4 sin (kπ/N). j=0 k=1 Graph of f (N; k) f(N;k)

4

1

0 j N/6 5N/6 ∏ j Put g(N; j) := k=1 f (N; k). j 0 ··· N/6 ··· 5N/6 ··· 1 f (N; k) < 1 1 > 1 1 < 1 g(N; j) 1 ↘ ↗ maximum ↘

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 16 / 23 Maximum of {g(N; j)}0≤j≤N−1 is g(N; 5N/6). ( √ ) ∑ − N−1 JN ; exp(2π 1/N) = j=0 g(N; j) and g(N; j) > 0. ⇓ ( √ ) g(N; 5N/6) ≤ JN ; exp(2π −1/N) ≤ N × g(N; 5N/6) ⇓ log g(N;5N/6) ≤ log JN ≤ log N log g(N;5N/6) N N N + N ⇓ log g(N; 5N/6) log J log N log g(N; 5N/6) lim ≤ lim N ≤ lim + lim N→∞ N N→∞ N N→∞ N N→∞ N ⇓ log J log g(N; 5N/6) lim N = lim N→∞ N N→∞ N

Volume conjecture for the figure-eight knot Limit of the sum is the limit of the maximum

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 17 / 23 ( √ ) ∑ − N−1 JN ; exp(2π 1/N) = j=0 g(N; j) and g(N; j) > 0. ⇓ ( √ ) g(N; 5N/6) ≤ JN ; exp(2π −1/N) ≤ N × g(N; 5N/6) ⇓ log g(N;5N/6) ≤ log JN ≤ log N log g(N;5N/6) N N N + N ⇓ log g(N; 5N/6) log J log N log g(N; 5N/6) lim ≤ lim N ≤ lim + lim N→∞ N N→∞ N N→∞ N N→∞ N ⇓ log J log g(N; 5N/6) lim N = lim N→∞ N N→∞ N

Volume conjecture for the figure-eight knot Limit of the sum is the limit of the maximum

Maximum of {g(N; j)}0≤j≤N−1 is g(N; 5N/6).

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 17 / 23 ⇓ ( √ ) g(N; 5N/6) ≤ JN ; exp(2π −1/N) ≤ N × g(N; 5N/6) ⇓ log g(N;5N/6) ≤ log JN ≤ log N log g(N;5N/6) N N N + N ⇓ log g(N; 5N/6) log J log N log g(N; 5N/6) lim ≤ lim N ≤ lim + lim N→∞ N N→∞ N N→∞ N N→∞ N ⇓ log J log g(N; 5N/6) lim N = lim N→∞ N N→∞ N

Volume conjecture for the figure-eight knot Limit of the sum is the limit of the maximum

Maximum of {g(N; j)}0≤j≤N−1 is g(N; 5N/6). ( √ ) ∑ − N−1 JN ; exp(2π 1/N) = j=0 g(N; j) and g(N; j) > 0.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 17 / 23 ( √ ) g(N; 5N/6) ≤ JN ; exp(2π −1/N) ≤ N × g(N; 5N/6) ⇓ log g(N;5N/6) ≤ log JN ≤ log N log g(N;5N/6) N N N + N ⇓ log g(N; 5N/6) log J log N log g(N; 5N/6) lim ≤ lim N ≤ lim + lim N→∞ N N→∞ N N→∞ N N→∞ N ⇓ log J log g(N; 5N/6) lim N = lim N→∞ N N→∞ N

Volume conjecture for the figure-eight knot Limit of the sum is the limit of the maximum

Maximum of {g(N; j)}0≤j≤N−1 is g(N; 5N/6). ( √ ) ∑ − N−1 JN ; exp(2π 1/N) = j=0 g(N; j) and g(N; j) > 0. ⇓

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 17 / 23 ⇓ log g(N;5N/6) ≤ log JN ≤ log N log g(N;5N/6) N N N + N ⇓ log g(N; 5N/6) log J log N log g(N; 5N/6) lim ≤ lim N ≤ lim + lim N→∞ N N→∞ N N→∞ N N→∞ N ⇓ log J log g(N; 5N/6) lim N = lim N→∞ N N→∞ N

Volume conjecture for the figure-eight knot Limit of the sum is the limit of the maximum

Maximum of {g(N; j)}0≤j≤N−1 is g(N; 5N/6). ( √ ) ∑ − N−1 JN ; exp(2π 1/N) = j=0 g(N; j) and g(N; j) > 0. ⇓ ( √ ) g(N; 5N/6) ≤ JN ; exp(2π −1/N) ≤ N × g(N; 5N/6)

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 17 / 23 ⇓ log g(N; 5N/6) log J log N log g(N; 5N/6) lim ≤ lim N ≤ lim + lim N→∞ N N→∞ N N→∞ N N→∞ N ⇓ log J log g(N; 5N/6) lim N = lim N→∞ N N→∞ N

Volume conjecture for the figure-eight knot Limit of the sum is the limit of the maximum

Maximum of {g(N; j)}0≤j≤N−1 is g(N; 5N/6). ( √ ) ∑ − N−1 JN ; exp(2π 1/N) = j=0 g(N; j) and g(N; j) > 0. ⇓ ( √ ) g(N; 5N/6) ≤ JN ; exp(2π −1/N) ≤ N × g(N; 5N/6) ⇓ log g(N;5N/6) ≤ log JN ≤ log N log g(N;5N/6) N N N + N

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 17 / 23 ⇓ log J log g(N; 5N/6) lim N = lim N→∞ N N→∞ N

Volume conjecture for the figure-eight knot Limit of the sum is the limit of the maximum

Maximum of {g(N; j)}0≤j≤N−1 is g(N; 5N/6). ( √ ) ∑ − N−1 JN ; exp(2π 1/N) = j=0 g(N; j) and g(N; j) > 0. ⇓ ( √ ) g(N; 5N/6) ≤ JN ; exp(2π −1/N) ≤ N × g(N; 5N/6) ⇓ log g(N;5N/6) ≤ log JN ≤ log N log g(N;5N/6) N N N + N ⇓ log g(N; 5N/6) log J log N log g(N; 5N/6) lim ≤ lim N ≤ lim + lim N→∞ N N→∞ N N→∞ N N→∞ N

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 17 / 23 Volume conjecture for the figure-eight knot Limit of the sum is the limit of the maximum

Maximum of {g(N; j)}0≤j≤N−1 is g(N; 5N/6). ( √ ) ∑ − N−1 JN ; exp(2π 1/N) = j=0 g(N; j) and g(N; j) > 0. ⇓ ( √ ) g(N; 5N/6) ≤ JN ; exp(2π −1/N) ≤ N × g(N; 5N/6) ⇓ log g(N;5N/6) ≤ log JN ≤ log N log g(N;5N/6) N N N + N ⇓ log g(N; 5N/6) log J log N log g(N; 5N/6) lim ≤ lim N ≤ lim + lim N→∞ N N→∞ N N→∞ N N→∞ N ⇓ log J log g(N; 5N/6) lim N = lim N→∞ N N→∞ N

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 17 / 23 5N/6 5N/6 1 ∑ 1 ∑ ( ) = lim log f (N; k) = 2 lim log 2 sin(kπ/N) N→∞ N N→∞ N ∫ k=1 k=1 2 5π/6 ( ) 2 = log 2 sin x dx = − Λ(5π/6) = 0.323066 ..., π 0 π ∫ − θ | | where Λ(θ) := 0 log 2 sin x dx is the Lobachevsky function. What is Λ(5π/6)?

( √ ) − log JN ; exp(2π 1/N) log g(N; 5N/6) lim = lim N→∞ N N→∞ N

Volume conjecture for the figure-eight knot Calculation of the limit of the maximum

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 18 / 23 5N/6 5N/6 1 ∑ 1 ∑ ( ) = lim log f (N; k) = 2 lim log 2 sin(kπ/N) N→∞ N N→∞ N ∫ k=1 k=1 2 5π/6 ( ) 2 = log 2 sin x dx = − Λ(5π/6) = 0.323066 ..., π 0 π ∫ − θ | | where Λ(θ) := 0 log 2 sin x dx is the Lobachevsky function. What is Λ(5π/6)?

Volume conjecture for the figure-eight knot Calculation of the limit of the maximum

( √ ) − log JN ; exp(2π 1/N) log g(N; 5N/6) lim = lim N→∞ N N→∞ N

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 18 / 23 5N/6 1 ∑ ( ) = 2 lim log 2 sin(kπ/N) N→∞ N ∫ k=1 2 5π/6 ( ) 2 = log 2 sin x dx = − Λ(5π/6) = 0.323066 ..., π 0 π ∫ − θ | | where Λ(θ) := 0 log 2 sin x dx is the Lobachevsky function. What is Λ(5π/6)?

Volume conjecture for the figure-eight knot Calculation of the limit of the maximum

( √ ) − log JN ; exp(2π 1/N) log g(N; 5N/6) lim = lim N→∞ N N→∞ N 5N/6 1 ∑ = lim log f (N; k) N→∞ N k=1

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 18 / 23 ∫ 2 5π/6 ( ) 2 = log 2 sin x dx = − Λ(5π/6) = 0.323066 ..., π 0 π ∫ − θ | | where Λ(θ) := 0 log 2 sin x dx is the Lobachevsky function. What is Λ(5π/6)?

Volume conjecture for the figure-eight knot Calculation of the limit of the maximum

( √ ) − log JN ; exp(2π 1/N) log g(N; 5N/6) lim = lim N→∞ N N→∞ N 5N/6 5N/6 1 ∑ 1 ∑ ( ) = lim log f (N; k) = 2 lim log 2 sin(kπ/N) N→∞ N N→∞ N k=1 k=1

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 18 / 23 2 = − Λ(5π/6) = 0.323066 ..., π ∫ − θ | | where Λ(θ) := 0 log 2 sin x dx is the Lobachevsky function. What is Λ(5π/6)?

Volume conjecture for the figure-eight knot Calculation of the limit of the maximum

( √ ) − log JN ; exp(2π 1/N) log g(N; 5N/6) lim = lim N→∞ N N→∞ N 5N/6 5N/6 1 ∑ 1 ∑ ( ) = lim log f (N; k) = 2 lim log 2 sin(kπ/N) N→∞ N N→∞ N ∫ k=1 k=1 2 5π/6 ( ) = log 2 sin x dx π 0

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 18 / 23 = 0.323066 ...,

∫ − θ | | where Λ(θ) := 0 log 2 sin x dx is the Lobachevsky function. What is Λ(5π/6)?

Volume conjecture for the figure-eight knot Calculation of the limit of the maximum

( √ ) − log JN ; exp(2π 1/N) log g(N; 5N/6) lim = lim N→∞ N N→∞ N 5N/6 5N/6 1 ∑ 1 ∑ ( ) = lim log f (N; k) = 2 lim log 2 sin(kπ/N) N→∞ N N→∞ N ∫ k=1 k=1 2 5π/6 ( ) 2 = log 2 sin x dx = − Λ(5π/6) π 0 π

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 18 / 23 ∫ − θ | | where Λ(θ) := 0 log 2 sin x dx is the Lobachevsky function. What is Λ(5π/6)?

Volume conjecture for the figure-eight knot Calculation of the limit of the maximum

( √ ) − log JN ; exp(2π 1/N) log g(N; 5N/6) lim = lim N→∞ N N→∞ N 5N/6 5N/6 1 ∑ 1 ∑ ( ) = lim log f (N; k) = 2 lim log 2 sin(kπ/N) N→∞ N N→∞ N ∫ k=1 k=1 2 5π/6 ( ) 2 = log 2 sin x dx = − Λ(5π/6) = 0.323066 ..., π 0 π

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 18 / 23 What is Λ(5π/6)?

Volume conjecture for the figure-eight knot Calculation of the limit of the maximum

( √ ) − log JN ; exp(2π 1/N) log g(N; 5N/6) lim = lim N→∞ N N→∞ N 5N/6 5N/6 1 ∑ 1 ∑ ( ) = lim log f (N; k) = 2 lim log 2 sin(kπ/N) N→∞ N N→∞ N ∫ k=1 k=1 2 5π/6 ( ) 2 = log 2 sin x dx = − Λ(5π/6) = 0.323066 ..., π 0 π ∫ − θ | | where Λ(θ) := 0 log 2 sin x dx is the Lobachevsky function.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 18 / 23 Volume conjecture for the figure-eight knot Calculation of the limit of the maximum

( √ ) − log JN ; exp(2π 1/N) log g(N; 5N/6) lim = lim N→∞ N N→∞ N 5N/6 5N/6 1 ∑ 1 ∑ ( ) = lim log f (N; k) = 2 lim log 2 sin(kπ/N) N→∞ N N→∞ N ∫ k=1 k=1 2 5π/6 ( ) 2 = log 2 sin x dx = − Λ(5π/6) = 0.323066 ..., π 0 π ∫ − θ | | where Λ(θ) := 0 log 2 sin x dx is the Lobachevsky function. What is Λ(5π/6)?

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 18 / 23 ∫ − θ | | Some properties of Λ(θ) := 0 log 2 sin x dx. Λ is an odd function and has period π. Λ(2θ) = 2Λ(∑θ) + 2Λ(θ + π/2). n−1 (Λ(nθ) = n k=1 Λ(θ + kπ/n) in general.) The first property is easy. To prove the second, we use the double angle formula of sine: sin(2x) = 2 sin x cos x. ⇒ log |2 sin(2x)| = log |2 sin x| + log |2 sin(x + π/2)|. So we have Λ(5π/6) = −Λ(π/6) Λ(π/3) = 2Λ(π/6) + 2Λ(2π/3) = 2Λ(π/6) − 2Λ(π/3) 3 ⇒ Λ(5π/6) = − Λ(π/3). ( √2 ) ⇒ 2π lim log JN ; exp(2π −1/N) /N = 6Λ(π/3) N→∞

Volume conjecture for the figure-eight knot Lobachevsky function Λ(θ)

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 19 / 23 Λ is an odd function and has period π. Λ(2θ) = 2Λ(∑θ) + 2Λ(θ + π/2). n−1 (Λ(nθ) = n k=1 Λ(θ + kπ/n) in general.) The first property is easy. To prove the second, we use the double angle formula of sine: sin(2x) = 2 sin x cos x. ⇒ log |2 sin(2x)| = log |2 sin x| + log |2 sin(x + π/2)|. So we have Λ(5π/6) = −Λ(π/6) Λ(π/3) = 2Λ(π/6) + 2Λ(2π/3) = 2Λ(π/6) − 2Λ(π/3) 3 ⇒ Λ(5π/6) = − Λ(π/3). ( √2 ) ⇒ 2π lim log JN ; exp(2π −1/N) /N = 6Λ(π/3) N→∞

Volume conjecture for the figure-eight knot

Lobachevsky function Λ(∫θ) − θ | | Some properties of Λ(θ) := 0 log 2 sin x dx.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 19 / 23 Λ(2θ) = 2Λ(∑θ) + 2Λ(θ + π/2). n−1 (Λ(nθ) = n k=1 Λ(θ + kπ/n) in general.) The first property is easy. To prove the second, we use the double angle formula of sine: sin(2x) = 2 sin x cos x. ⇒ log |2 sin(2x)| = log |2 sin x| + log |2 sin(x + π/2)|. So we have Λ(5π/6) = −Λ(π/6) Λ(π/3) = 2Λ(π/6) + 2Λ(2π/3) = 2Λ(π/6) − 2Λ(π/3) 3 ⇒ Λ(5π/6) = − Λ(π/3). ( √2 ) ⇒ 2π lim log JN ; exp(2π −1/N) /N = 6Λ(π/3) N→∞

Volume conjecture for the figure-eight knot

Lobachevsky function Λ(∫θ) − θ | | Some properties of Λ(θ) := 0 log 2 sin x dx. Λ is an odd function and has period π.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 19 / 23 The first property is easy. To prove the second, we use the double angle formula of sine: sin(2x) = 2 sin x cos x. ⇒ log |2 sin(2x)| = log |2 sin x| + log |2 sin(x + π/2)|. So we have Λ(5π/6) = −Λ(π/6) Λ(π/3) = 2Λ(π/6) + 2Λ(2π/3) = 2Λ(π/6) − 2Λ(π/3) 3 ⇒ Λ(5π/6) = − Λ(π/3). ( √2 ) ⇒ 2π lim log JN ; exp(2π −1/N) /N = 6Λ(π/3) N→∞

Volume conjecture for the figure-eight knot

Lobachevsky function Λ(∫θ) − θ | | Some properties of Λ(θ) := 0 log 2 sin x dx. Λ is an odd function and has period π. Λ(2θ) = 2Λ(∑θ) + 2Λ(θ + π/2). n−1 (Λ(nθ) = n k=1 Λ(θ + kπ/n) in general.)

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 19 / 23 To prove the second, we use the double angle formula of sine: sin(2x) = 2 sin x cos x. ⇒ log |2 sin(2x)| = log |2 sin x| + log |2 sin(x + π/2)|. So we have Λ(5π/6) = −Λ(π/6) Λ(π/3) = 2Λ(π/6) + 2Λ(2π/3) = 2Λ(π/6) − 2Λ(π/3) 3 ⇒ Λ(5π/6) = − Λ(π/3). ( √2 ) ⇒ 2π lim log JN ; exp(2π −1/N) /N = 6Λ(π/3) N→∞

Volume conjecture for the figure-eight knot

Lobachevsky function Λ(∫θ) − θ | | Some properties of Λ(θ) := 0 log 2 sin x dx. Λ is an odd function and has period π. Λ(2θ) = 2Λ(∑θ) + 2Λ(θ + π/2). n−1 (Λ(nθ) = n k=1 Λ(θ + kπ/n) in general.) The first property is easy.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 19 / 23 sin(2x) = 2 sin x cos x. ⇒ log |2 sin(2x)| = log |2 sin x| + log |2 sin(x + π/2)|. So we have Λ(5π/6) = −Λ(π/6) Λ(π/3) = 2Λ(π/6) + 2Λ(2π/3) = 2Λ(π/6) − 2Λ(π/3) 3 ⇒ Λ(5π/6) = − Λ(π/3). ( √2 ) ⇒ 2π lim log JN ; exp(2π −1/N) /N = 6Λ(π/3) N→∞

Volume conjecture for the figure-eight knot

Lobachevsky function Λ(∫θ) − θ | | Some properties of Λ(θ) := 0 log 2 sin x dx. Λ is an odd function and has period π. Λ(2θ) = 2Λ(∑θ) + 2Λ(θ + π/2). n−1 (Λ(nθ) = n k=1 Λ(θ + kπ/n) in general.) The first property is easy. To prove the second, we use the double angle formula of sine:

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 19 / 23 ⇒ log |2 sin(2x)| = log |2 sin x| + log |2 sin(x + π/2)|. So we have Λ(5π/6) = −Λ(π/6) Λ(π/3) = 2Λ(π/6) + 2Λ(2π/3) = 2Λ(π/6) − 2Λ(π/3) 3 ⇒ Λ(5π/6) = − Λ(π/3). ( √2 ) ⇒ 2π lim log JN ; exp(2π −1/N) /N = 6Λ(π/3) N→∞

Volume conjecture for the figure-eight knot

Lobachevsky function Λ(∫θ) − θ | | Some properties of Λ(θ) := 0 log 2 sin x dx. Λ is an odd function and has period π. Λ(2θ) = 2Λ(∑θ) + 2Λ(θ + π/2). n−1 (Λ(nθ) = n k=1 Λ(θ + kπ/n) in general.) The first property is easy. To prove the second, we use the double angle formula of sine: sin(2x) = 2 sin x cos x.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 19 / 23 So we have Λ(5π/6) = −Λ(π/6) Λ(π/3) = 2Λ(π/6) + 2Λ(2π/3) = 2Λ(π/6) − 2Λ(π/3) 3 ⇒ Λ(5π/6) = − Λ(π/3). ( √2 ) ⇒ 2π lim log JN ; exp(2π −1/N) /N = 6Λ(π/3) N→∞

Volume conjecture for the figure-eight knot

Lobachevsky function Λ(∫θ) − θ | | Some properties of Λ(θ) := 0 log 2 sin x dx. Λ is an odd function and has period π. Λ(2θ) = 2Λ(∑θ) + 2Λ(θ + π/2). n−1 (Λ(nθ) = n k=1 Λ(θ + kπ/n) in general.) The first property is easy. To prove the second, we use the double angle formula of sine: sin(2x) = 2 sin x cos x. ⇒ log |2 sin(2x)| = log |2 sin x| + log |2 sin(x + π/2)|.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 19 / 23 3 ⇒ Λ(5π/6) = − Λ(π/3). ( √2 ) ⇒ 2π lim log JN ; exp(2π −1/N) /N = 6Λ(π/3) N→∞

Volume conjecture for the figure-eight knot

Lobachevsky function Λ(∫θ) − θ | | Some properties of Λ(θ) := 0 log 2 sin x dx. Λ is an odd function and has period π. Λ(2θ) = 2Λ(∑θ) + 2Λ(θ + π/2). n−1 (Λ(nθ) = n k=1 Λ(θ + kπ/n) in general.) The first property is easy. To prove the second, we use the double angle formula of sine: sin(2x) = 2 sin x cos x. ⇒ log |2 sin(2x)| = log |2 sin x| + log |2 sin(x + π/2)|. So we have Λ(5π/6) = −Λ(π/6) Λ(π/3) = 2Λ(π/6) + 2Λ(2π/3) = 2Λ(π/6) − 2Λ(π/3)

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 19 / 23 ( √ ) ⇒ 2π lim log JN ; exp(2π −1/N) /N = 6Λ(π/3) N→∞

Volume conjecture for the figure-eight knot

Lobachevsky function Λ(∫θ) − θ | | Some properties of Λ(θ) := 0 log 2 sin x dx. Λ is an odd function and has period π. Λ(2θ) = 2Λ(∑θ) + 2Λ(θ + π/2). n−1 (Λ(nθ) = n k=1 Λ(θ + kπ/n) in general.) The first property is easy. To prove the second, we use the double angle formula of sine: sin(2x) = 2 sin x cos x. ⇒ log |2 sin(2x)| = log |2 sin x| + log |2 sin(x + π/2)|. So we have Λ(5π/6) = −Λ(π/6) Λ(π/3) = 2Λ(π/6) + 2Λ(2π/3) = 2Λ(π/6) − 2Λ(π/3) 3 ⇒ Λ(5π/6) = − Λ(π/3). 2

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 19 / 23 Volume conjecture for the figure-eight knot

Lobachevsky function Λ(∫θ) − θ | | Some properties of Λ(θ) := 0 log 2 sin x dx. Λ is an odd function and has period π. Λ(2θ) = 2Λ(∑θ) + 2Λ(θ + π/2). n−1 (Λ(nθ) = n k=1 Λ(θ + kπ/n) in general.) The first property is easy. To prove the second, we use the double angle formula of sine: sin(2x) = 2 sin x cos x. ⇒ log |2 sin(2x)| = log |2 sin x| + log |2 sin(x + π/2)|. So we have Λ(5π/6) = −Λ(π/6) Λ(π/3) = 2Λ(π/6) + 2Λ(2π/3) = 2Λ(π/6) − 2Λ(π/3) 3 ⇒ Λ(5π/6) = − Λ(π/3). ( √2 ) ⇒ 2π lim log JN ; exp(2π −1/N) /N = 6Λ(π/3) N→∞

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 19 / 23 What is 6Λ(π/3)? Theorem (W. Thurston)

c e

= C B ∪ D’ B’ b ′ ′ A=A ,B=B , h C’ D C=C ′,D=D′ a A d g A’ f

We can regard both pieces in the right hand side as regular ideal hyperbolic tetrahedra. ⇒ S3 \ possesses a complete hyperbolic structure.

Volume conjecture for the figure-eight knot Decomposition of S 3 \ into two tetrahedra

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 20 / 23 Theorem (W. Thurston)

c e

= C B ∪ D’ B’ b ′ ′ A=A ,B=B , h C’ D C=C ′,D=D′ a A d g A’ f

We can regard both pieces in the right hand side as regular ideal hyperbolic tetrahedra. ⇒ S3 \ possesses a complete hyperbolic structure.

Volume conjecture for the figure-eight knot Decomposition of S 3 \ into two tetrahedra

What is 6Λ(π/3)?

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 20 / 23 ⇒ S3 \ possesses a complete hyperbolic structure.

Volume conjecture for the figure-eight knot Decomposition of S 3 \ into two tetrahedra

What is 6Λ(π/3)? Theorem (W. Thurston)

c e

= C B ∪ D’ B’ b ′ ′ A=A ,B=B , h C’ D C=C ′,D=D′ a A d g A’ f

We can regard both pieces in the right hand side as regular ideal hyperbolic tetrahedra.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 20 / 23 Volume conjecture for the figure-eight knot Decomposition of S 3 \ into two tetrahedra

What is 6Λ(π/3)? Theorem (W. Thurston)

c e

= C B ∪ D’ B’ b ′ ′ A=A ,B=B , h C’ D C=C ′,D=D′ a A d g A’ f

We can regard both pieces in the right hand side as regular ideal hyperbolic tetrahedra. ⇒ S3 \ possesses a complete hyperbolic structure.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 20 / 23 √ H3 { | } dx2+dy 2+dt2 := (x, y, t) t > 0 : with hyperbolic metric ds := t . Ideal hyperbolic tetrahedron: tetrahedron with geodesic faces with four vertices in the boundary at infinity. We may assume ▶ One vertex is at ∞. ▶ The other three are on xy-plane. Ideal hyperbolic tetrahedron Top view Ideal hyperbolic tetrahedron is ∆(α, β, γ) defined (up to isometry) by the similarity class of this triangle. β α γ β α γ Vol(∆(α, β, γ)) = Λ(α)+Λ(β)+Λ(γ).

Volume conjecture for the figure-eight knot Ideal hyperbolic tetrahedron

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 21 / 23 Ideal hyperbolic tetrahedron: tetrahedron with geodesic faces with four vertices in the boundary at infinity. We may assume ▶ One vertex is at ∞. ▶ The other three are on xy-plane. Ideal hyperbolic tetrahedron Top view Ideal hyperbolic tetrahedron is ∆(α, β, γ) defined (up to isometry) by the similarity class of this triangle. β α γ β α γ Vol(∆(α, β, γ)) = Λ(α)+Λ(β)+Λ(γ).

Volume conjecture for the figure-eight knot Ideal hyperbolic tetrahedron √ H3 { | } dx2+dy 2+dt2 := (x, y, t) t > 0 : with hyperbolic metric ds := t .

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 21 / 23 We may assume ▶ One vertex is at ∞. ▶ The other three are on xy-plane. Ideal hyperbolic tetrahedron Top view Ideal hyperbolic tetrahedron is ∆(α, β, γ) defined (up to isometry) by the similarity class of this triangle. β α γ β α γ Vol(∆(α, β, γ)) = Λ(α)+Λ(β)+Λ(γ).

Volume conjecture for the figure-eight knot Ideal hyperbolic tetrahedron √ H3 { | } dx2+dy 2+dt2 := (x, y, t) t > 0 : with hyperbolic metric ds := t . Ideal hyperbolic tetrahedron: tetrahedron with geodesic faces with four vertices in the boundary at infinity.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 21 / 23 Ideal hyperbolic tetrahedron Top view Ideal hyperbolic tetrahedron is ∆(α, β, γ) defined (up to isometry) by the similarity class of this triangle. β α γ β α γ Vol(∆(α, β, γ)) = Λ(α)+Λ(β)+Λ(γ).

Volume conjecture for the figure-eight knot Ideal hyperbolic tetrahedron √ H3 { | } dx2+dy 2+dt2 := (x, y, t) t > 0 : with hyperbolic metric ds := t . Ideal hyperbolic tetrahedron: tetrahedron with geodesic faces with four vertices in the boundary at infinity. We may assume ▶ One vertex is at ∞. ▶ The other three are on xy-plane.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 21 / 23 Top view Ideal hyperbolic tetrahedron is defined (up to isometry) by the similarity class of this triangle.

β α γ Vol(∆(α, β, γ)) = Λ(α)+Λ(β)+Λ(γ).

Volume conjecture for the figure-eight knot Ideal hyperbolic tetrahedron √ H3 { | } dx2+dy 2+dt2 := (x, y, t) t > 0 : with hyperbolic metric ds := t . Ideal hyperbolic tetrahedron: tetrahedron with geodesic faces with four vertices in the boundary at infinity. We may assume ▶ One vertex is at ∞. ▶ The other three are on xy-plane. Ideal hyperbolic tetrahedron ∆(α, β, γ)

β α γ

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 21 / 23 Ideal hyperbolic tetrahedron is defined (up to isometry) by the similarity class of this triangle.

Vol(∆(α, β, γ)) = Λ(α)+Λ(β)+Λ(γ).

Volume conjecture for the figure-eight knot Ideal hyperbolic tetrahedron √ H3 { | } dx2+dy 2+dt2 := (x, y, t) t > 0 : with hyperbolic metric ds := t . Ideal hyperbolic tetrahedron: tetrahedron with geodesic faces with four vertices in the boundary at infinity. We may assume ▶ One vertex is at ∞. ▶ The other three are on xy-plane. Ideal hyperbolic tetrahedron Top view ∆(α, β, γ)

β α γ β α γ

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 21 / 23 Volume conjecture for the figure-eight knot Ideal hyperbolic tetrahedron √ H3 { | } dx2+dy 2+dt2 := (x, y, t) t > 0 : with hyperbolic metric ds := t . Ideal hyperbolic tetrahedron: tetrahedron with geodesic faces with four vertices in the boundary at infinity. We may assume ▶ One vertex is at ∞. ▶ The other three are on xy-plane. Ideal hyperbolic tetrahedron Top view Ideal hyperbolic tetrahedron is ∆(α, β, γ) defined (up to isometry) by the similarity class of this triangle. β α γ β α γ Vol(∆(α, β, γ)) = Λ(α)+Λ(β)+Λ(γ).

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 21 / 23 =6Λ(π/3) =2 Vol(regular ideal hyperbolic tetrahedron) ( ) = Vol S3 \ .

This amazing fact was first observed by R. Kashaev and proved by T. Ekholm. On the other hand the complement of is a Seifert fibered space, that is, it has( a geometry) of surface × circle. ⇒ Vol S3 \ = 0. In fact Kashaev and O. Tirkkonen proved that √ log JN (T (p,q);exp(2π −1/N)) 2π limN→∞ N = 0 for any T (p, q).

( √ ) log JN ; exp(2π −1/N) 2π lim N→∞ N

Volume conjecture for the figure-eight knot Proof of VC - conclusion

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 22 / 23 =6Λ(π/3) =2 Vol(regular ideal hyperbolic tetrahedron) ( ) = Vol S3 \ .

This amazing fact was first observed by R. Kashaev and proved by T. Ekholm. On the other hand the complement of is a Seifert fibered space, that is, it has( a geometry) of surface × circle. ⇒ Vol S3 \ = 0. In fact Kashaev and O. Tirkkonen proved that √ log JN (T (p,q);exp(2π −1/N)) 2π limN→∞ N = 0 for any torus knot T (p, q).

Volume conjecture for the figure-eight knot Proof of VC - conclusion

( √ ) log JN ; exp(2π −1/N) 2π lim N→∞ N

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 22 / 23 =2 Vol(regular ideal hyperbolic tetrahedron) ( ) = Vol S3 \ .

This amazing fact was first observed by R. Kashaev and proved by T. Ekholm. On the other hand the complement of is a Seifert fibered space, that is, it has( a geometry) of surface × circle. ⇒ Vol S3 \ = 0. In fact Kashaev and O. Tirkkonen proved that √ log JN (T (p,q);exp(2π −1/N)) 2π limN→∞ N = 0 for any torus knot T (p, q).

Volume conjecture for the figure-eight knot Proof of VC - conclusion

( √ ) log JN ; exp(2π −1/N) 2π lim N→∞ N =6Λ(π/3)

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 22 / 23 ( ) = Vol S3 \ .

This amazing fact was first observed by R. Kashaev and proved by T. Ekholm. On the other hand the complement of is a Seifert fibered space, that is, it has( a geometry) of surface × circle. ⇒ Vol S3 \ = 0. In fact Kashaev and O. Tirkkonen proved that √ log JN (T (p,q);exp(2π −1/N)) 2π limN→∞ N = 0 for any torus knot T (p, q).

Volume conjecture for the figure-eight knot Proof of VC - conclusion

( √ ) log JN ; exp(2π −1/N) 2π lim N→∞ N =6Λ(π/3) =2 Vol(regular ideal hyperbolic tetrahedron)

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 22 / 23 This amazing fact was first observed by R. Kashaev and proved by T. Ekholm. On the other hand the complement of is a Seifert fibered space, that is, it has( a geometry) of surface × circle. ⇒ Vol S3 \ = 0. In fact Kashaev and O. Tirkkonen proved that √ log JN (T (p,q);exp(2π −1/N)) 2π limN→∞ N = 0 for any torus knot T (p, q).

Volume conjecture for the figure-eight knot Proof of VC - conclusion

( √ ) log JN ; exp(2π −1/N) 2π lim N→∞ N =6Λ(π/3) =2 Vol(regular ideal hyperbolic tetrahedron) ( ) = Vol S3 \ .

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 22 / 23 On the other hand the complement of is a Seifert fibered space, that is, it has( a geometry) of surface × circle. ⇒ Vol S3 \ = 0. In fact Kashaev and O. Tirkkonen proved that √ log JN (T (p,q);exp(2π −1/N)) 2π limN→∞ N = 0 for any torus knot T (p, q).

Volume conjecture for the figure-eight knot Proof of VC - conclusion

( √ ) log JN ; exp(2π −1/N) 2π lim N→∞ N =6Λ(π/3) =2 Vol(regular ideal hyperbolic tetrahedron) ( ) = Vol S3 \ .

This amazing fact was first observed by R. Kashaev and proved by T. Ekholm.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 22 / 23 ( ) ⇒ Vol S3 \ = 0. In fact Kashaev and O. Tirkkonen proved that √ log JN (T (p,q);exp(2π −1/N)) 2π limN→∞ N = 0 for any torus knot T (p, q).

Volume conjecture for the figure-eight knot Proof of VC - conclusion

( √ ) log JN ; exp(2π −1/N) 2π lim N→∞ N =6Λ(π/3) =2 Vol(regular ideal hyperbolic tetrahedron) ( ) = Vol S3 \ .

This amazing fact was first observed by R. Kashaev and proved by T. Ekholm. On the other hand the complement of is a Seifert fibered space, that is, it has a geometry of surface × circle.

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 22 / 23 Volume conjecture for the figure-eight knot Proof of VC - conclusion

( √ ) log JN ; exp(2π −1/N) 2π lim N→∞ N =6Λ(π/3) =2 Vol(regular ideal hyperbolic tetrahedron) ( ) = Vol S3 \ .

This amazing fact was first observed by R. Kashaev and proved by T. Ekholm. On the other hand the complement of is a Seifert fibered space, that is, it has( a geometry) of surface × circle. ⇒ Vol S3 \ = 0. In fact Kashaev and O. Tirkkonen proved that √ log JN (T (p,q);exp(2π −1/N)) 2π limN→∞ N = 0 for any torus knot T (p, q).

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 22 / 23 figure-eight knot (hyperbolic) (T. Ekholm (1999)) torus (including ) (Seifert fibered) (R. Kashaev + O. Tirkkonen (2000)), iterated torus knots (Seifert fibered + Seifert fibered) (R. van der Veen (2008)), Whitehead doubles of torus knots of (2, 2n + 1) (Seifert fibered + hyperbolic) (H. Zheng (2007)), (2, 2m + 1)-cable of the figure-eight knot (hyperbolic + Seifert fibered) (T. Lˆeand A. Tran (2010)).

52 knot (hyperbolic) (R. Kashaev and Y. Yokota, T. Oh- tsuki) hyperbolic knots with six crossings (T. Ohtsuki and Y. Yokota)

VC is proved for ... So far the Volume Conjecture is proved for

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 23 / 23 torus knots (including ) (Seifert fibered) (R. Kashaev + O. Tirkkonen (2000)), iterated torus knots (Seifert fibered + Seifert fibered) (R. van der Veen (2008)), Whitehead doubles of torus knots of (2, 2n + 1) (Seifert fibered + hyperbolic) (H. Zheng (2007)), (2, 2m + 1)-cable of the figure-eight knot (hyperbolic + Seifert fibered) (T. Lˆeand A. Tran (2010)).

52 knot (hyperbolic) (R. Kashaev and Y. Yokota, T. Oh- tsuki) hyperbolic knots with six crossings (T. Ohtsuki and Y. Yokota)

VC is proved for ... So far the Volume Conjecture is proved for figure-eight knot (hyperbolic) (T. Ekholm (1999))

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 23 / 23 iterated torus knots (Seifert fibered + Seifert fibered) (R. van der Veen (2008)), Whitehead doubles of torus knots of (2, 2n + 1) (Seifert fibered + hyperbolic) (H. Zheng (2007)), (2, 2m + 1)-cable of the figure-eight knot (hyperbolic + Seifert fibered) (T. Lˆeand A. Tran (2010)).

52 knot (hyperbolic) (R. Kashaev and Y. Yokota, T. Oh- tsuki) hyperbolic knots with six crossings (T. Ohtsuki and Y. Yokota)

VC is proved for ... So far the Volume Conjecture is proved for figure-eight knot (hyperbolic) (T. Ekholm (1999)) torus knots (including ) (Seifert fibered) (R. Kashaev + O. Tirkkonen (2000)),

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 23 / 23 Whitehead doubles of torus knots of (2, 2n + 1) (Seifert fibered + hyperbolic) (H. Zheng (2007)), (2, 2m + 1)-cable of the figure-eight knot (hyperbolic + Seifert fibered) (T. Lˆeand A. Tran (2010)).

52 knot (hyperbolic) (R. Kashaev and Y. Yokota, T. Oh- tsuki) hyperbolic knots with six crossings (T. Ohtsuki and Y. Yokota)

VC is proved for ... So far the Volume Conjecture is proved for figure-eight knot (hyperbolic) (T. Ekholm (1999)) torus knots (including ) (Seifert fibered) (R. Kashaev + O. Tirkkonen (2000)), iterated torus knots (Seifert fibered + Seifert fibered) (R. van der Veen (2008)),

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 23 / 23 (2, 2m + 1)-cable of the figure-eight knot (hyperbolic + Seifert fibered) (T. Lˆeand A. Tran (2010)).

52 knot (hyperbolic) (R. Kashaev and Y. Yokota, T. Oh- tsuki) hyperbolic knots with six crossings (T. Ohtsuki and Y. Yokota)

VC is proved for ... So far the Volume Conjecture is proved for figure-eight knot (hyperbolic) (T. Ekholm (1999)) torus knots (including ) (Seifert fibered) (R. Kashaev + O. Tirkkonen (2000)), iterated torus knots (Seifert fibered + Seifert fibered) (R. van der Veen (2008)), Whitehead doubles of torus knots of (2, 2n + 1) (Seifert fibered + hyperbolic) (H. Zheng (2007)),

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 23 / 23 52 knot (hyperbolic) (R. Kashaev and Y. Yokota, T. Oh- tsuki) hyperbolic knots with six crossings (T. Ohtsuki and Y. Yokota)

VC is proved for ... So far the Volume Conjecture is proved for figure-eight knot (hyperbolic) (T. Ekholm (1999)) torus knots (including ) (Seifert fibered) (R. Kashaev + O. Tirkkonen (2000)), iterated torus knots (Seifert fibered + Seifert fibered) (R. van der Veen (2008)), Whitehead doubles of torus knots of (2, 2n + 1) (Seifert fibered + hyperbolic) (H. Zheng (2007)), (2, 2m + 1)-cable of the figure-eight knot (hyperbolic + Seifert fibered) (T. Lˆeand A. Tran (2010)).

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 23 / 23 hyperbolic knots with six crossings (T. Ohtsuki and Y. Yokota)

VC is proved for ... So far the Volume Conjecture is proved for figure-eight knot (hyperbolic) (T. Ekholm (1999)) torus knots (including ) (Seifert fibered) (R. Kashaev + O. Tirkkonen (2000)), iterated torus knots (Seifert fibered + Seifert fibered) (R. van der Veen (2008)), Whitehead doubles of torus knots of (2, 2n + 1) (Seifert fibered + hyperbolic) (H. Zheng (2007)), (2, 2m + 1)-cable of the figure-eight knot (hyperbolic + Seifert fibered) (T. Lˆeand A. Tran (2010)).

52 knot (hyperbolic) (R. Kashaev and Y. Yokota, T. Oh- tsuki)

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 23 / 23 VC is proved for ... So far the Volume Conjecture is proved for figure-eight knot (hyperbolic) (T. Ekholm (1999)) torus knots (including ) (Seifert fibered) (R. Kashaev + O. Tirkkonen (2000)), iterated torus knots (Seifert fibered + Seifert fibered) (R. van der Veen (2008)), Whitehead doubles of torus knots of (2, 2n + 1) (Seifert fibered + hyperbolic) (H. Zheng (2007)), (2, 2m + 1)-cable of the figure-eight knot (hyperbolic + Seifert fibered) (T. Lˆeand A. Tran (2010)).

52 knot (hyperbolic) (R. Kashaev and Y. Yokota, T. Oh- tsuki) hyperbolic knots with six crossings (T. Ohtsuki and Y. Yokota)

Hitoshi Murakami (Tohoku University ) Volume Conjecture, I IISER, Pune, 19th December, 2018 23 / 23