Volume conjecture

Last updated
Volume conjecture
Field Knot theory
Conjectured by
  • Hitoshi Murakami
  • Jun Murakami
  • Rinat Kashaev
Known cases
Consequences Vassiliev invariants detect the unknot

In the branch of mathematics called knot theory, the volume conjecture is an open problem that relates quantum invariants of knots to the hyperbolic geometry of their complements.

Contents

Statement

Let O denote the unknot. For any knot , let be the Kashaev invariant of , which may be defined as

,

where is the -Colored Jones polynomial of . The volume conjecture states that [1]

,

where is the simplicial volume of the complement of in the 3-sphere, defined as follows. By the JSJ decomposition, the complement may be uniquely decomposed into a system of tori

with hyperbolic and Seifert-fibered. The simplicial volume is then defined as the sum

,

where is the hyperbolic volume of the hyperbolic manifold . [1]

As a special case, if is a hyperbolic knot, then the JSJ decomposition simply reads , and by definition the simplicial volume agrees with the hyperbolic volume .

History

The Kashaev invariant was first introduced by Rinat M. Kashaev in 1994 and 1995 for hyperbolic links as a state sum using the theory of quantum dilogarithms. [2] [3] Kashaev stated the formula of the volume conjecture in the case of hyperbolic knots in 1997. [4]

Murakami & Murakami (2001) pointed out that the Kashaev invariant is related to the colored Jones polynomial by replacing the variable with the root of unity . They used an R-matrix as the discrete Fourier transform for the equivalence of these two descriptions. This paper was the first to state the volume conjecture in its modern form using the simplicial volume. They also prove that the volume conjecture implies the following conjecture of Victor Vasiliev:

If all Vassiliev invariants of a knot agree with those of the unknot, then the knot is the unknot.

The key observation in their proof is that if every Vassiliev invariant of a knot is trivial, then for any .

Status

The volume conjecture is open for general knots, and it is known to be false for arbitrary links. The volume conjecture has been verified in many special cases, including:

Relation to Chern-Simons theory

Using complexification, Murakami et al. (2002) proved that for a hyperbolic knot ,

,

where is the Chern–Simons invariant. They established a relationship between the complexified colored Jones polynomial and Chern–Simons theory.

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References

Notes

  1. 1 2 Murakami 2010, p. 17.
  2. Kashaev, R.M. (1994-12-28). "Quantum Dilogarithm as a 6j-Symbol". Modern Physics Letters A . 09 (40): 3757–3768. arXiv: hep-th/9411147 . Bibcode:1994MPLA....9.3757K. doi:10.1142/S0217732394003610. ISSN   0217-7323.
  3. Kashaev, R.M. (1995-06-21). "A Link Invariant from Quantum Dilogarithm". Modern Physics Letters A. 10 (19): 1409–1418. arXiv: q-alg/9504020 . Bibcode:1995MPLA...10.1409K. doi:10.1142/S0217732395001526. ISSN   0217-7323.
  4. Kashaev, R. M. (1997). "The Hyperbolic Volume of Knots from the Quantum Dilogarithm". Letters in Mathematical Physics . 39 (3): 269–275. arXiv: q-alg/9601025 . Bibcode:1997LMaPh..39..269K. doi:10.1023/A:1007364912784.
  5. 1 2 3 4 5 Murakami 2010, p. 22.
  6. 1 2 Zheng, Hao (2007), "Proof of the volume conjecture for Whitehead doubles of a family of torus knots", Chinese Annals of Mathematics, Series B : 375–388, arXiv: math/0508138

Sources