8 20

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8_19

8_21

Contents

Image:8 20.gif
(KnotPlot image)

See the full Rolfsen Knot Table.

Visit 8 20's page at the Knot Server (KnotPlot driven, includes 3D interactive images!)

Visit 8_20's page at Knotilus!

Visit 8 20's page at the original Knot Atlas!

8_20 is also known as the pretzel knot P(3,-3,2).

Its complement contains no complete totally geodesic immersed surfaces.[citation needed]


[edit] Knot presentations

Planar diagram presentation X4251 X8493 X5,12,6,13 X13,16,14,1 X9,14,10,15 X15,10,16,11 X11,6,12,7 X2837
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 [3,21,2-]


Minimum Braid Representative A Morse Link Presentation An Arc Presentation
Image:BraidPart1.gifImage:BraidPart1.gifImage:BraidPart1.gifImage:BraidPart0.gifImage:BraidPart3.gifImage:BraidPart3.gifImage:BraidPart3.gifImage:BraidPart0.gif
Image:BraidPart2.gifImage:BraidPart2.gifImage:BraidPart2.gifImage:BraidPart3.gifImage:BraidPart4.gifImage:BraidPart4.gifImage:BraidPart4.gifImage:BraidPart3.gif
Image:BraidPart0.gifImage:BraidPart0.gifImage:BraidPart0.gifImage:BraidPart4.gifImage:BraidPart0.gifImage:BraidPart0.gifImage:BraidPart0.gifImage:BraidPart4.gif

Length is 8, width is 3,

Braid index is 3

Image:8 20_ML.gif Image:8 20_AP.gif
[{3, 8}, {2, 4}, {1, 3}, {11, 9}, {8, 10}, {9, 5}, {4, 6}, {5, 7}, {6, 11}, {10, 2}, {7, 1}]

[edit Notes on presentations of 8 20]

Knot 8_20.
Knot 8_20.
A graph, knot 8_20.
A graph, knot 8_20.

[edit] 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 [-6][-2]
Hyperbolic Volume 4.1249
A-Polynomial See Data:8 20/A-polynomial

[edit Notes for 8 20's three dimensional invariants]
8_20 ribbon diagram from A. Kawauchi's text.

Ribbon diagram for 8_20
Ribbon diagram for 8_20

[edit] Four dimensional invariants

Smooth 4 genus 0
Topological 4 genus 0
Concordance genus 0
Rasmussen s-Invariant 0

[edit Notes for 8 20's four dimensional invariants]

[edit] Polynomial invariants

Alexander polynomial t2−2t + 3−2t−1 + t−2
Conway polynomial z4 + 2z2 + 1
2nd Alexander ideal (db, data sources) {1}
Determinant and Signature { 9, 0 }
Jones polynomial q + 2−q−1 + 2q−2q−3 + q−4q−5
HOMFLY-PT polynomial (db, data sources) z2a4−2a4 + z4a2 + 4z2a2 + 4a2z2−1
Kauffman polynomial (db, data sources) a4z6 + a2z6 + a5z5 + 2a3z5 + az5−4a4z4−4a2z4−4a5z3−7a3z3−3az3 + 4a4z2 + 6a2z2 + 2z2 + 3a5z + 5a3z + 3az + za−1−2a4−4a2−1
The A2 invariant q16q14q12 + 2q8 + 2q6 + 2q4 + q2q−4
The G2 invariant q80 + q76q74−2q68 + q66q64q62q60−2q58−3q52q50q48 + q44−2q42 + q40 + q38 + 2q36 + q34 + 2q30 + 2q28 + 3q26 + 2q22 + 3q20 + q18 + q16 + q14 + 3q10−2q6 + q4 + 1−q−2−2q−4q−12q−14q−20 + q−24

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

Same Alexander/Conway Polynomial: {10_140, K11n73, K11n74,}

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

[edit] Vassiliev invariants

V2 and V3: (2, -2)
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
8 −16 32 \frac{172}{3} \frac{20}{3} −128 -\frac{640}{3} -\frac{64}{3} −48 \frac{256}{3} 128 \frac{1376}{3} \frac{160}{3} \frac{11911}{15} -\frac{524}{15} \frac{15484}{45} \frac{233}{9} \frac{631}{15}

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.

[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 = 0 is the signature of 8 20. Nonzero entries off the critical diagonals (if any exist) are highlighted in red.   
\ r
  \  
j \
-5-4-3-2-101χ
3      1-1
1     1 1
-1    12 1
-3   1   1
-5   1   1
-7 11    0
-9       0
-111      -1
Integral Khovanov Homology

(db, data source)

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

Back to the top.

8_19

8_21

Retrieved from "http://katlas.org/wiki/8_20"
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