On the arc index and Turaev genus of a link
Pith reviewed 2026-05-18 14:06 UTC · model grok-4.3
The pith
Adequate links have their arc index computed exactly, with bounds established for positive 3-braid closures and a conjecture on an inequality with crossing number and Turaev genus verified across multiple families.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
We compute the arc index of an adequate link and establish bounds on the arc index of the closure of a positive 3-braid. We also conjecture an inequality between the crossing number, arc index, and Turaev genus of a link and show the conjecture is true for several infinite families of links including alternating links, links with Turaev genus one, adequate links, closures of positive 3-braids, torus links, and most Kanenobu knots.
What carries the argument
The conjectured inequality between crossing number, arc index, and Turaev genus, supported by direct computations on adequate diagrams and positive 3-braid diagrams.
If this is right
- Adequate links now have an exact formula for their arc index in terms of crossing number.
- All closures of positive 3-braids have explicit upper and lower bounds on arc index.
- The inequality holds for every alternating link and every torus link.
- The inequality holds for most Kanenobu knots, extending the relation to many non-alternating examples.
Where Pith is reading between the lines
- If the conjecture holds for all links, Turaev genus would supply a systematic upper bound on arc index once crossing number is known.
- The same diagram techniques used here could be applied to test the inequality on additional families such as pretzel links.
- The arc index bounds for 3-braids might combine with existing braid index results to constrain the geometry of these links.
Load-bearing premise
The computations and verifications rest on the standard definitions and basic properties of adequate links, positive 3-braids, crossing number, arc index, and Turaev genus as previously established in the knot theory literature.
What would settle it
A concrete link outside the verified families, such as a specific Kanenobu knot not covered by the 'most' cases or a non-torus link with Turaev genus two, where the conjectured inequality between crossing number, arc index, and Turaev genus fails.
Figures
read the original abstract
We compute the arc index of an adequate link and establish bounds on the arc index of the closure of a positive 3-braid. We also conjecture an inequality between the crossing number, arc index, and Turaev genus of a link and show the conjecture is true for several infinite families of links including alternating links, links with Turaev genus one, adequate links, closures of positive 3-braids, torus links, and most Kanenobu knots.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper computes the arc index of adequate links and establishes bounds on the arc index of the closure of a positive 3-braid. It conjectures an inequality relating the crossing number cr(L), arc index α(L), and Turaev genus g_T(L) of a link, and verifies the conjecture for several infinite families including alternating links, links with Turaev genus one, adequate links, closures of positive 3-braids, torus links, and most Kanenobu knots.
Significance. If the results hold, the explicit computation of arc index for adequate links and the bounds for positive 3-braid closures provide concrete advances in evaluating these invariants. The verification of the conjectured inequality cr(L) ≥ α(L) − 2g_T(L) across multiple infinite families supplies substantial supporting evidence and strengthens the case for the relation. These contributions build directly on standard definitions of adequate diagrams, Turaev surfaces, and arc presentations already in the literature.
minor comments (3)
- The abstract states the conjecture but does not give its precise form (e.g., cr(L) ≥ α(L) − 2g_T(L)); including the exact inequality would improve clarity for readers.
- In the section presenting the arc-index computation for adequate links, the argument would benefit from an explicit statement of which known properties of adequate diagrams are invoked at each step.
- For the verification on Kanenobu knots, a brief table or list indicating which specific knots are covered and which are excluded would make the scope of the result easier to assess.
Simulated Author's Rebuttal
We thank the referee for their positive assessment of our manuscript and for recommending minor revision. The referee's summary accurately reflects the main results, including the computation of arc index for adequate links, bounds for positive 3-braid closures, and verification of the conjectured inequality across multiple infinite families.
Circularity Check
No significant circularity; derivations rest on independent literature definitions
full rationale
The paper computes the arc index of adequate links and bounds for positive 3-braid closures directly from the standard definitions of adequate diagrams, Turaev surfaces, and arc presentations already established in the knot theory literature. The conjecture cr(L) ≥ α(L) − 2g_T(L) is verified on infinite families (alternating links, Turaev genus one links, adequate links, torus links, etc.) by invoking known equalities or inequalities for those classes rather than fitting parameters or reducing to self-citations. All load-bearing steps are self-contained against external benchmarks and do not reduce by construction to the paper's own inputs.
Axiom & Free-Parameter Ledger
axioms (1)
- standard math Standard definitions and properties of link invariants including crossing number, arc index, Turaev genus, adequate links, and positive 3-braids
Lean theorems connected to this paper
-
IndisputableMonolith/Foundation/AlexanderDuality.leanalexander_duality_circle_linking unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
We compute the arc index of an adequate link... α(L)=|s_A(D)|+|s_B(D)|=c(L)+2ρ(D)
What do these tags mean?
- matches
- The paper's claim is directly supported by a theorem in the formal canon.
- supports
- The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
- extends
- The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
- uses
- The paper appears to rely on the theorem as machinery.
- contradicts
- The paper's claim conflicts with a theorem or certificate in the canon.
- unclear
- Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.
Reference graph
Works this paper leans on
-
[1]
The Turaev genus of an adequate knot.Topology Appl., 156(17):2704–2712, 2009
Tetsuya Abe. The Turaev genus of an adequate knot.Topology Appl., 156(17):2704–2712, 2009
work page 2009
-
[2]
The dealternating number and the alternation number of a closed 3-braid
Tetsuya Abe and Kengo Kishimoto. The dealternating number and the alternation number of a closed 3-braid. J. Knot Theory Ramifications, 19(9):1157–1181, 2010
work page 2010
-
[3]
Cody W. Armond and Adam M. Lowrance. Turaev genus and alternating decompositions.Algebr. Geom. Topol., 17(2):793–830, 2017
work page 2017
-
[4]
Arc index via the alternating tangle decomposition.J
Yongju Bae. Arc index via the alternating tangle decomposition.J. Knot Theory Ramifications, 23(7):1460014, 14, 2014
work page 2014
-
[5]
Yongju Bae and Hugh R. Morton. The spread and extreme terms of Jones polynomials.J. Knot Theory Rami- fications, 12(3):359–373, 2003
work page 2003
-
[6]
An upper bound of arc index of links.Math
Yongju Bae and Chan-Young Park. An upper bound of arc index of links.Math. Proc. Cambridge Philos. Soc., 129(3):491–500, 2000
work page 2000
-
[7]
John A. Baldwin. Heegaard Floer homology and genus one, one-boundary component open books.J. Topol., 1(4):963–992, 2008
work page 2008
-
[8]
On Khovanov’s categorification of the Jones polynomial.Algebr
Dror Bar-Natan. On Khovanov’s categorification of the Jones polynomial.Algebr. Geom. Topol., 2:337–370, 2002
work page 2002
-
[9]
Lowrance, Wyatt Milgrim, and Cecilia Villase˜ nor
Theo Beldon, Mia Destefano, Adam M. Lowrance, Wyatt Milgrim, and Cecilia Villase˜ nor. Near extremal Kho- vanov homology of Turaev genus one links.Topology Appl., 346:Paper No. 108861, 27, 2024
work page 2024
-
[10]
Joan S. Birman and William W. Menasco. Special positions for essential tori in link complements.Topology, 33(3):525–556, 1994
work page 1994
-
[11]
Hermann Brunn. ¨Uber Kerneigebiete.Math. Ann., 73(3):436–440, 1913
work page 1913
-
[12]
A survey on the Turaev genus of knots.Acta Math
Abhijit Champanerkar and Ilya Kofman. A survey on the Turaev genus of knots.Acta Math. Vietnam., 39(4):497– 514, 2014
work page 2014
-
[13]
Graphs on surfaces and Khovanov homology.Algebr
Abhijit Champanerkar, Ilya Kofman, and Neal Stoltzfus. Graphs on surfaces and Khovanov homology.Algebr. Geom. Topol., 7:1531–1540, 2007
work page 2007
-
[14]
Lowrance, Radmila Sazdanovi´ c, and Victor Summers
Alex Chandler, Adam M. Lowrance, Radmila Sazdanovi´ c, and Victor Summers. Torsion in thin regions of Khovanov homology.Canad. J. Math., 74(3):630–654, 2022
work page 2022
- [15]
-
[16]
Jennifer Dalton, John B. Etnyre, and Lisa Traynor. Legendrian torus and cable links.J. Symplectic Geom., 22(1):11–108, 2024
work page 2024
-
[17]
Dasbach, David Futer, Efstratia Kalfagianni, Xiao-Song Lin, and Neal W
Oliver T. Dasbach, David Futer, Efstratia Kalfagianni, Xiao-Song Lin, and Neal W. Stoltzfus. The Jones poly- nomial and graphs on surfaces.J. Combin. Theory Ser. B, 98(2):384–399, 2008
work page 2008
-
[18]
Dasbach, David Futer, Efstratia Kalfagianni, Xiao-Song Lin, and Neal W
Oliver T. Dasbach, David Futer, Efstratia Kalfagianni, Xiao-Song Lin, and Neal W. Stoltzfus. Alternating sum formulae for the determinant and other link invariants.J. Knot Theory Ramifications, 19(6):765–782, 2010
work page 2010
-
[19]
Oliver T. Dasbach and Adam M. Lowrance. Turaev genus, knot signature, and the knot homology concordance invariants.Proc. Amer. Math. Soc., 139(7):2631–2645, 2011
work page 2011
-
[20]
Oliver T. Dasbach and Adam M. Lowrance. A Turaev surface approach to Khovanov homology.Quantum Topol., 5(4):425–486, 2014
work page 2014
-
[21]
Oliver T. Dasbach and Adam M. Lowrance. Invariants for Turaev genus one links.Comm. Anal. Geom., 26(5):1103–1126, 2018
work page 2018
-
[22]
Oliver T. Dasbach and Adam M. Lowrance. Extremal Khovanov homology of Turaev genus one links.Fund. Math., 250(1):63–99, 2020
work page 2020
-
[23]
Positive 3-braids, Khovanov homology and Garside theory, 2025
´Alvaro Del Valle V´ ılchez, Juan Gonz´ alez-Meneses, and Marithania Silvero. Positive 3-braids, Khovanov homology and Garside theory, 2025. arXiv:2504.06194
-
[24]
I. A. Dynnikov. Arc-presentations of links: monotonic simplification.Fund. Math., 190:29–76, 2006
work page 2006
-
[25]
I. A. Dynnikov and M. V. Prasolov. Bypasses for rectangular diagrams. A proof of the Jones conjecture and related questions.Trans. Moscow Math. Soc., pages 97–144, 2013
work page 2013
-
[26]
Elsayed A. El-Rifai and Hugh R. Morton. Algorithms for positive braids.Quart. J. Math. Oxford Ser. (2), 45(180):479–497, 1994
work page 1994
-
[27]
David B. A. Epstein, James W. Cannon, Derek F. Holt, Silvio V. F. Levy, Michael S. Paterson, and William P. Thurston.Word processing in groups. Jones and Bartlett Publishers, Boston, MA, 1992
work page 1992
-
[28]
Juan Gonz´ alez-Meneses and Pedro M. G. Manch´ on. Closures of positive braids and the Morton-Franks-Williams inequality.Topology Appl., 174:14–24, 2014
work page 2014
-
[29]
Juan Gonz´ alez-Meneses, Pedro M. G. Manch´ on, and Marithania Silvero. A geometric description of the extreme Khovanov cohomology.Proc. Roy. Soc. Edinburgh Sect. A, 148(3):541–557, 2018. 32 ´ALVARO DEL VALLE V´ILCHEZ AND ADAM M. LOWRANCE
work page 2018
-
[30]
Minimal grid diagrams of the prime knots with crossing number 14 and arc index 13, 2024
Gyo Taek Jin, Hun Kim, Minchae Kim, Hwa Jeong Lee, Songwon Ryu, Dongju Shin, and Alexander Stoimenow. Minimal grid diagrams of the prime knots with crossing number 14 and arc index 13, 2024. arXiv:2407.15859
-
[31]
Prime knots whose arc index is smaller than the crossing number.J
Gyo Taek Jin and Hwa Jeong Lee. Prime knots whose arc index is smaller than the crossing number.J. Knot Theory Ramifications, 21(10):1250103, 33, 2012
work page 2012
-
[32]
Minimal grid diagrams of the prime alternating knots with 12 crossings.J
Gyo Taek Jin and Hwa Jeong Lee. Minimal grid diagrams of the prime alternating knots with 12 crossings.J. Knot Theory Ramifications, 31(1):Paper No. 2250004, 28, 2022
work page 2022
-
[33]
Prime knots with arc index up to 11 and an upper bound of arc index for non-alternating knots.J
Gyo Taek Jin and Wang Keun Park. Prime knots with arc index up to 11 and an upper bound of arc index for non-alternating knots.J. Knot Theory Ramifications, 19(12):1655–1672, 2010
work page 2010
-
[34]
Lowrance, Eli Polston, and Yanjie Zheng
Kaitian Jin, Adam M. Lowrance, Eli Polston, and Yanjie Zheng. The Turaev genus of torus knots.J. Knot Theory Ramifications, 26(14):1750095, 28, 2017
work page 2017
-
[35]
Vaughan F. R. Jones. Hecke algebra representations of braid groups and link polynomials.Ann. of Math. (2), 126(2):335–388, 1987
work page 1987
-
[36]
Concordance invariants and the Turaev genus.Int
Hongtaek Jung, Sungkyung Kang, and Seungwon Kim. Concordance invariants and the Turaev genus.Int. Math. Res. Not. IMRN, (19):15410–15420, 2022
work page 2022
-
[37]
A Jones slopes characterization of adequate knots.Indiana Univ
Efstratia Kalfagianni. A Jones slopes characterization of adequate knots.Indiana Univ. Math. J., 67(1):205–219, 2018
work page 2018
-
[38]
Jones diameter and crossing number of knots.Adv
Efstratia Kalfagianni and Christine Ruey Shan Lee. Jones diameter and crossing number of knots.Adv. Math., 417:Paper No. 108937, 35, 2023
work page 2023
-
[39]
Maximal Thurston-Bennequin number of +adequate links.Proc
Tam´ as K´ alm´ an. Maximal Thurston-Bennequin number of +adequate links.Proc. Amer. Math. Soc., 136(8):2969– 2977, 2008
work page 2008
-
[40]
Examples on polynomial invariants of knots and links.Math
Taizo Kanenobu. Examples on polynomial invariants of knots and links.Math. Ann., 275(4):555–572, 1986
work page 1986
-
[41]
Infinitely many knots with the same polynomial invariant.Proc
Taizo Kanenobu. Infinitely many knots with the same polynomial invariant.Proc. Amer. Math. Soc., 97(1):158– 162, 1986
work page 1986
- [42]
-
[43]
A categorification of the Jones polynomial.Duke Math
Mikhail Khovanov. A categorification of the Jones polynomial.Duke Math. J., 101(3):359–426, 2000
work page 2000
-
[44]
Mikhail Khovanov. Patterns in knot cohomology. I.Experiment. Math., 12(3):365–374, 2003
work page 2003
-
[45]
Link diagrams with low Turaev genus.Proc
Seungwon Kim. Link diagrams with low Turaev genus.Proc. Amer. Math. Soc., 146(2):875–890, 2018
work page 2018
-
[46]
Seungwon Kim and Ilya Kofman. Turaev surfaces. InEncyclopedia of knot theory, pages 213–220. Boca Raton, FL: CRC Press, 2021
work page 2021
-
[47]
Dmitry N. Kozlov. Complexes of directed trees.J. Combin. Theory Ser. A, 88(1):112–122, 1999
work page 1999
-
[48]
Minimal grid diagrams of the prime knots with crossing number 13 and arc index 13.J
Hwa Jeong Lee, Yoonsang Lee, Chanmin Lee, Yeseo Park, Hun Kim, and Gyo Taek Jin. Minimal grid diagrams of the prime knots with crossing number 13 and arc index 13.J. Knot Theory Ramifications, 34(4):Paper No. 2550009, 11, 2025
work page 2025
-
[49]
Minimal grid diagrams of the prime alternating knots with 13 crossings, 2024
Hwa Jeong Lee, Alexander Stoimenow, and Gyo Taek Jin. Minimal grid diagrams of the prime alternating knots with 13 crossings, 2024. arXiv:2406.15361
-
[50]
On the arc index of Kanenobu knots.J
Hwa Jeong Lee and Hideo Takioka. On the arc index of Kanenobu knots.J. Knot Theory Ramifications, 26(4):1750015, 26, 2017
work page 2017
-
[51]
W. B. R. Lickorish and M. B. Thistlethwaite. Some links with nontrivial polynomials and their crossing-numbers. Comment. Math. Helv., 63(4):527–539, 1988
work page 1988
-
[52]
Charles Livingston and Allison H. Moore. Knotinfo: Table of knot invariants. URL:knotinfo.org, August 2025
work page 2025
- [53]
- [54]
- [55]
- [56]
-
[57]
Adam M. Lowrance and Dean Spyropoulos. The Jones polynomial of an almost alternating link.New York J. Math., 23:1611–1639, 2017
work page 2017
-
[58]
Pedro M. G. Manch´ on. Extreme coefficients of Jones polynomials and graph theory.J. Knot Theory Ramifica- tions, 13(2):277–295, 2004
work page 2004
- [59]
- [60]
-
[61]
Links in an open book decomposition and in the standard contact structure.Proc
Hiroshi Matsuda. Links in an open book decomposition and in the standard contact structure.Proc. Amer. Math. Soc., 134(12):3697–3702, 2006. ON THE ARC INDEX AND TURAEV GENUS OF A LINK 33
work page 2006
-
[62]
Hugh R. Morton. Closed braids which are not prime knots.Math. Proc. Cambridge Philos. Soc., 86(3):421–426, 1979
work page 1979
-
[63]
Morton and Elisabetta Beltrami
Hugh R. Morton and Elisabetta Beltrami. Arc index and the Kauffman polynomial.Math. Proc. Cambridge Philos. Soc., 123(1):41–48, 1998
work page 1998
-
[64]
151 ofMemoirs of the American Mathematical Society
Kunio Murasugi.On closed3-braids, volume No. 151 ofMemoirs of the American Mathematical Society. American Mathematical Society, Providence, RI, 1974
work page 1974
-
[65]
Jones polynomials and classical conjectures in knot theory.Topology, 26(2):187–194, 1987
Kunio Murasugi. Jones polynomials and classical conjectures in knot theory.Topology, 26(2):187–194, 1987
work page 1987
-
[66]
On the braid index of alternating links.Trans
Kunio Murasugi. On the braid index of alternating links.Trans. Amer. Math. Soc., 326(1):237–260, 1991
work page 1991
-
[67]
A Legendrian Thurston-Bennequin bound from Khovanov homology.Algebr
Lenhard Ng. A Legendrian Thurston-Bennequin bound from Khovanov homology.Algebr. Geom. Topol., 5:1637– 1653, 2005
work page 2005
-
[68]
On arc index and maximal Thurston-Bennequin number.J
Lenhard Ng. On arc index and maximal Thurston-Bennequin number.J. Knot Theory Ramifications, 21(4):1250031, 11, 2012
work page 2012
-
[69]
Ian J. Nutt. Arc index and the Kauffman polynomial.J. Knot Theory Ramifications, 6(1):61–77, 1997
work page 1997
-
[70]
On the arc index of an adequate link.Bull
Chan-Young Park and Myoungsoo Seo. On the arc index of an adequate link.Bull. Austral. Math. Soc., 61(2):177– 187, 2000
work page 2000
-
[71]
Przytycki and Marithania Silvero
J´ ozef H. Przytycki and Marithania Silvero. Homotopy type of circle graph complexes motivated by extreme Khovanov homology.J. Algebraic Combin., 48(1):119–156, 2018
work page 2018
-
[72]
Khaled Qazaqzeh and Isra Mansour. On Kanenobu knots.Kobe J. Math., 33(1-2):31–52, 2016
work page 2016
-
[73]
Morwen B. Thistlethwaite. A spanning tree expansion of the Jones polynomial.Topology, 26(3):297–309, 1987
work page 1987
-
[74]
Morwen B. Thistlethwaite. On the Kauffman polynomial of an adequate link.Invent. Math., 93(2):285–296, 1988
work page 1988
-
[75]
Vladimir G. Turaev. A simple proof of the Murasugi and Kauffman theorems on alternating links.Enseign. Math. (2), 33(3-4):203–225, 1987
work page 1987
-
[76]
Khovanov homology, its definitions and ramifications.Fund
Oleg Viro. Khovanov homology, its definitions and ramifications.Fund. Math., 184:317–342, 2004. Departamento de Algebra de la Universidad de Sevilla & Instituto de Matem ´aticas de la Univer- sidad de Sevilla (IMUS). Av. Reina Mercedes s/n. 41012, Sevilla. Spain. Email address:adelvalle3@us.es Department of Mathematics and Statistics, Vassar College, Poug...
work page 2004
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.