8 21

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8 20.gif

8_20

9 1.gif

9_1

8 21.gif
(KnotPlot image)

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Knot presentations

Planar diagram presentation X1425 X3849 X12,6,13,5 X13,16,14,1 X9,14,10,15 X15,10,16,11 X6,12,7,11 X7283
Gauss code -1, 8, -2, 1, 3, -7, -8, 2, -5, 6, 7, -3, -4, 5, -6, 4
Dowker-Thistlethwaite code 4 8 -12 2 14 -6 16 10
Conway Notation [21,21,2-]


Minimum Braid Representative A Morse Link Presentation An Arc Presentation
BraidPart3.gifBraidPart3.gifBraidPart3.gifBraidPart0.gifBraidPart1.gifBraidPart1.gifBraidPart0.gifBraidPart0.gif
BraidPart4.gifBraidPart4.gifBraidPart4.gifBraidPart3.gifBraidPart2.gifBraidPart2.gifBraidPart3.gifBraidPart3.gif
BraidPart0.gifBraidPart0.gifBraidPart0.gifBraidPart4.gifBraidPart0.gifBraidPart0.gifBraidPart4.gifBraidPart4.gif

Length is 8, width is 3,

Braid index is 3

8 21 ML.gif 8 21 AP.gif
[{9, 3}, {2, 7}, {6, 8}, {7, 9}, {4, 1}, {3, 6}, {5, 2}, {8, 4}, {1, 5}]

[edit Notes on presentations of 8 21]

Knot 8_21.
A graph: knot 8_21.
A part of a knot and a part of a graph.

Three dimensional invariants

Symmetry type Reversible
Unknotting number 1
3-genus 2
Bridge index 3
Super bridge index 4
Nakanishi index 1
Maximal Thurston-Bennequin number [-9][1]
Hyperbolic Volume 6.78371
A-Polynomial See Data:8 21/A-polynomial

[edit Notes for 8 21's three dimensional invariants]

Four dimensional invariants

Smooth 4 genus
Topological 4 genus
Concordance genus
Rasmussen s-Invariant -2

[edit Notes for 8 21's four dimensional invariants]

Polynomial invariants

Alexander polynomial
Conway polynomial
2nd Alexander ideal (db, data sources)
Determinant and Signature { 15, -2 }
Jones polynomial
HOMFLY-PT polynomial (db, data sources)
Kauffman polynomial (db, data sources)
The A2 invariant
The G2 invariant

"Similar" Knots (within the Atlas)

Same Alexander/Conway Polynomial: {10_136,}

Same Jones Polynomial (up to mirroring, ): {}

Vassiliev invariants

V2 and V3: (0, 1)
V2,1 through V6,9:
V2,1 V3,1 V4,1 V4,2 V4,3 V5,1 V5,2 V5,3 V5,4 V6,1 V6,2 V6,3 V6,4 V6,5 V6,6 V6,7 V6,8 V6,9

V2,1 through V6,9 were provided by Petr Dunin-Barkowski <barkovs@itep.ru>, Andrey Smirnov <asmirnov@itep.ru>, and Alexei Sleptsov <sleptsov@itep.ru> and uploaded on October 2010 by User:Drorbn. Note that they are normalized differently than V2 and V3.

Khovanov Homology

The coefficients of the monomials are shown, along with their alternating sums (fixed , alternation over ). The squares with yellow highlighting are those on the "critical diagonals", where or , where -2 is the signature of 8 21. Nonzero entries off the critical diagonals (if any exist) are highlighted in red.   
\ r
  \  
j \
-6-5-4-3-2-10χ
-1      22
-3     110
-5    21 1
-7   11  0
-9  12   -1
-11 11    0
-13 1     -1
-151      1
Integral Khovanov Homology

(db, data source)

  

The Coloured Jones Polynomials