8 18

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Image:8 18.gif
(KnotPlot image)

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Visit 8 18's page at the original Knot Atlas!


Logo of the International Guild of Knot Tyers [1]
Logo of the International Guild of Knot Tyers [1]
A charity logo in Porto [2]
A charity logo in Porto [2]
A laser cut by Tom Longtin [3]
A laser cut by Tom Longtin [3]
Knot in (pseudo-)Celtic decorative form
Knot in (pseudo-)Celtic decorative form

[edit] Knot presentations

Planar diagram presentation X6271 X8394 X16,11,1,12 X2,14,3,13 X4,15,5,16 X10,6,11,5 X12,7,13,8 X14,10,15,9
Gauss code 1, -4, 2, -5, 6, -1, 7, -2, 8, -6, 3, -7, 4, -8, 5, -3
Dowker-Thistlethwaite code 6 8 10 12 14 16 2 4
Conway Notation [8*]


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

Length is 8, width is 3,

Braid index is 3

Image:8 18_ML.gif Image:8 18_AP.gif
[{3, 10}, {2, 8}, {4, 9}, {5, 3}, {1, 4}, {7, 2}, {8, 6}, {10, 7}, {9, 5}, {6, 1}]

[edit Notes on presentations of 8 18]

Knot 8_18.
Knot 8_18.
A graph, knot 8_18.
A graph, knot 8_18.

[edit] Three dimensional invariants

Symmetry type Fully amphicheiral
Unknotting number 2
3-genus 3
Bridge index 3
Super bridge index 4
Nakanishi index 2
Maximal Thurston-Bennequin number [-5][-5]
Hyperbolic Volume 12.3509
A-Polynomial See Data:8 18/A-polynomial

[edit Notes for 8 18's three dimensional invariants]

[edit] Four dimensional invariants

Smooth 4 genus 1
Topological 4 genus 1
Concordance genus [1,3]
Rasmussen s-Invariant 0

[edit Notes for 8 18's four dimensional invariants]

[edit] Polynomial invariants

Alexander polynomial t3 + 5t2−10t + 13−10t−1 + 5t−2t−3
Conway polynomial z6z4 + z2 + 1
2nd Alexander ideal (db, data sources) \left\{t^2-t+1\right\}
Determinant and Signature { 45, 0 }
Jones polynomial q4−4q3 + 6q2−7q + 9−7q−1 + 6q−2−4q−3 + q−4
HOMFLY-PT polynomial (db, data sources) z6 + a2z4 + z4a−2−3z4 + a2z2 + z2a−2z2a2a−2 + 3
Kauffman polynomial (db, data sources) 3az7 + 3z7a−1 + 6a2z6 + 6z6a−2 + 12z6 + 4a3z5 + 3az5 + 3z5a−1 + 4z5a−3 + a4z4−9a2z4−9z4a−2 + z4a−4−20z4−4a3z3−9az3−9z3a−1−4z3a−3 + 3a2z2 + 3z2a−2 + 6z2 + az + za−1 + a2 + a−2 + 3
The A2 invariant q12−2q10q6q4 + 4q2 + 1 + 4q−2q−4q−6−2q−10 + q−12
The G2 invariant q66−3q64 + 6q62−10q60 + 8q58−4q56−5q54 + 23q52−36q50 + 48q48−38q46 + 7q44 + 28q42−67q40 + 84q38−71q36 + 29q34 + 17q32−58q30 + 77q28−56q26 + 8q24 + 34q22−59q20 + 45q18−6q16−45q14 + 81q12−81q10 + 64q8−11q6−48q4 + 97q2−111 + 97q−2−48q−4−11q−6 + 64q−8−81q−10 + 81q−12−45q−14−6q−16 + 45q−18−59q−20 + 34q−22 + 8q−24−56q−26 + 77q−28−58q−30 + 17q−32 + 29q−34−71q−36 + 84q−38−67q−40 + 28q−42 + 7q−44−38q−46 + 48q−48−36q−50 + 23q−52−5q−54−4q−56 + 8q−58−10q−60 + 6q−62−3q−64 + q−66

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

Same Alexander/Conway Polynomial: {9_24, K11n85, K11n164,}

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

[edit] Vassiliev invariants

V2 and V3: (1, 0)

[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 18. Nonzero entries off the critical diagonals (if any exist) are highlighted in red.   
\ r
  \  
j \
-4-3-2-101234χ
9        11
7       3 -3
5      31 2
3     43  -1
1    53   2
-1   35    2
-3  34     -1
-5 13      2
-7 3       -3
-91        1
Integral Khovanov Homology

(db, data source)

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

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