8 19

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Contents

Image:8 19.gif
(KnotPlot image)

See the full Rolfsen Knot Table.

Visit 8 19's page at the Knot Server (KnotPlot driven, includes 3D interactive images!)

Visit 8_19's page at Knotilus!

Visit 8 19's page at the original Knot Atlas!

8 19 is the first non-obvious torus knot in the table - it is in fact T(4,3). It is also the pretzel knot P(3,3,-2).

8_19 is the first non-homologically thin knot in the Rolfsen table. (That is, it's the first knot whose Khovanov homology has 'off-diagonal' elements.)

[edit] Knot presentations

Planar diagram presentation X4251 X8493 X9,15,10,14 X5,13,6,12 X13,7,14,6 X11,1,12,16 X15,11,16,10 X2837
Gauss code 1, -8, 2, -1, -4, 5, 8, -2, -3, 7, -6, 4, -5, 3, -7, 6
Dowker-Thistlethwaite code 4 8 -12 2 -14 -16 -6 -10
Conway Notation [3,3,2-]


Minimum Braid Representative A Morse Link Presentation An Arc Presentation
Image:BraidPart1.gifImage:BraidPart1.gifImage:BraidPart1.gifImage:BraidPart0.gifImage:BraidPart1.gifImage:BraidPart1.gifImage:BraidPart1.gifImage:BraidPart0.gif
Image:BraidPart2.gifImage:BraidPart2.gifImage:BraidPart2.gifImage:BraidPart1.gifImage:BraidPart2.gifImage:BraidPart2.gifImage:BraidPart2.gifImage:BraidPart1.gif
Image:BraidPart0.gifImage:BraidPart0.gifImage:BraidPart0.gifImage:BraidPart2.gifImage:BraidPart0.gifImage:BraidPart0.gifImage:BraidPart0.gifImage:BraidPart2.gif

Length is 8, width is 3,

Braid index is 3

Image:8 19_ML.gif Image:8 19_AP.gif
[{4, 10}, {3, 5}, {1, 4}, {6, 9}, {5, 8}, {2, 6}, {10, 3}, {9, 7}, {8, 2}, {7, 1}]

[edit Notes on presentations of 8 19]

Knot 8_19.
Knot 8_19.
A graph which shows knot 8_19.
A graph which shows knot 8_19.
A part of a knot and a part of a graph.
A part of a knot and a part of a graph.

[edit] Three dimensional invariants

Symmetry type Reversible
Unknotting number 3
3-genus 3
Bridge index 3
Super bridge index 4
Nakanishi index 1
Maximal Thurston-Bennequin number [5][-12]
Hyperbolic Volume Not hyperbolic
A-Polynomial See Data:8 19/A-polynomial

[edit Notes for 8 19's three dimensional invariants]

[edit] Four dimensional invariants

Smooth 4 genus 3
Topological 4 genus 3
Concordance genus 3
Rasmussen s-Invariant -6

[edit Notes for 8 19's four dimensional invariants]

[edit] Polynomial invariants

Alexander polynomial t3t2 + 1−t−2 + t−3
Conway polynomial z6 + 5z4 + 5z2 + 1
2nd Alexander ideal (db, data sources) {1}
Determinant and Signature { 3, 6 }
Jones polynomial q8 + q5 + q3
HOMFLY-PT polynomial (db, data sources) z6a−6 + 6z4a−6z4a−8 + 10z2a−6−5z2a−8 + 5a−6−5a−8 + a−10
Kauffman polynomial (db, data sources) z6a−6 + z6a−8 + z5a−7 + z5a−9−6z4a−6−6z4a−8−5z3a−7−5z3a−9 + 10z2a−6 + 10z2a−8 + 5za−7 + 5za−9−5a−6−5a−8a−10
The A2 invariant q−10 + q−12 + 2q−14 + 2q−16 + 2q−18q−22−2q−24−2q−26q−28 + q−32
The G2 invariant q−50 + q−52 + q−54 + q−56 + q−58 + q−60 + 2q−62 + 2q−64 + q−66 + q−68 + 2q−70 + 2q−72 + 2q−74 + q−76 + q−80 + 2q−82q−94−2q−96q−98q−100−2q−102−2q−104−2q−106q−108q−110−2q−112−2q−114q−116q−122q−124 + q−126 + q−128 + q−136 + q−138 + q−144

[edit] "Similar" Knots (within the Atlas)

Same Alexander/Conway Polynomial: {}

Same Jones Polynomial (up to mirroring, q\leftrightarrow q^{-1}): {}

[edit] Vassiliev invariants

V2 and V3: (5, 10)

[edit] Khovanov Homology

The coefficients of the monomials trqj are shown, along with their alternating sums χ (fixed j, alternation over r). The squares with yellow highlighting are those on the "critical diagonals", where j−2r = s + 1 or j−2r = s−1, where s = 6 is the signature of 8 19. Nonzero entries off the critical diagonals (if any exist) are highlighted in red.   
\ r
  \  
j \
012345χ
17     1-1
15     1-1
13   11 0
11    1 1
9  1   1
71     1
51     1
Integral Khovanov Homology

(db, data source)

  
\dim{\mathcal G}_{2r+i}\operatorname{KH}^r_{\mathbb Z} i = 3 i = 5 i = 7
r = 0 {\mathbb Z} {\mathbb Z}
r = 1
r = 2 {\mathbb Z}
r = 3 {\mathbb Z}_2 {\mathbb Z}
r = 4 {\mathbb Z} {\mathbb Z}
r = 5 {\mathbb Z} {\mathbb Z}

[edit] The Coloured Jones Polynomials

[edit] Computer Talk

Much of the above data can be recomputed by Mathematica using the package KnotTheory`. See A Sample KnotTheory` Session, or any of the Computer Talk sections above.

[edit] Modifying This Page

Read me first: Modifying Knot Pages

See/edit the Rolfsen Knot Page master template (intermediate).

See/edit the Rolfsen_Splice_Base (expert).

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