8 20
From Knot Atlas
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![]() (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! |
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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 | |||
Length is 8, width is 3, Braid index is 3 |
| ![]() [{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]
KnotTheory`. Your input (in red) is realistic; all else should have the same content as in a real mathematica session, but with different formatting.
(The path below may be different on your system, and possibly also the KnotTheory` date)
In[1]:=
| AppendTo[$Path, "C:/drorbn/projects/KAtlas/"];
<< KnotTheory`
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Loading KnotTheory` version of May 31, 2006, 14:15:20.091.
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In[3]:=
| K = Knot["8 20"];
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In[4]:=
| PD[K]
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KnotTheory::loading: Loading precomputed data in PD4Knots`.
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Out[4]=
| X4251 X8493 X5,12,6,13 X13,16,14,1 X9,14,10,15 X15,10,16,11 X11,6,12,7 X2837 |
In[5]:=
| GaussCode[K]
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Out[5]=
| 1, -8, 2, -1, -3, 7, 8, -2, -5, 6, -7, 3, -4, 5, -6, 4 |
In[6]:=
| DTCode[K]
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Out[6]=
| 4 8 -12 2 -14 -6 -16 -10 |
(The path below may be different on your system)
In[7]:=
| AppendTo[$Path, "C:/bin/LinKnot/"];
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In[8]:=
| ConwayNotation[K]
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Out[8]=
| [3,21,2-] |
In[9]:=
| br = BR[K]
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KnotTheory::credits: The minimum braids representing the knots with up to 10 crossings were provided by Thomas Gittings. See arXiv:math.GT/0401051.
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Out[9]=
| BR(3,{1,1,1,−2,−1,−1,−1,−2}) |
In[10]:=
| {First[br], Crossings[br], BraidIndex[K]}
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KnotTheory::credits: The braid index data known to KnotTheory` is taken from Charles Livingston's http://www.indiana.edu/~knotinfo/.
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KnotTheory::loading: Loading precomputed data in IndianaData`.
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Out[10]=
| { 3, 8, 3 } |
In[11]:=
| Show[BraidPlot[br]]
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Out[11]=
| -Graphics- |
In[12]:=
| Show[DrawMorseLink[K]]
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KnotTheory::credits: "MorseLink was added to KnotTheory` by Siddarth Sankaran at the University of Toronto in the summer of 2005."
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KnotTheory::credits: "DrawMorseLink was written by Siddarth Sankaran at the University of Toronto in the summer of 2005."
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Out[12]=
| -Graphics- |
In[13]:=
| ap = ArcPresentation[K]
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Out[13]=
| ArcPresentation[{3, 8}, {2, 4}, {1, 3}, {11, 9}, {8, 10}, {9, 5}, {4, 6}, {5, 7}, {6, 11}, {10, 2}, {7, 1}] |
In[14]:=
| Draw[ap]
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Out[14]=
| -Graphics- |
[edit] Three dimensional invariants
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[edit Notes for 8 20's three dimensional invariants]
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[edit] Four dimensional invariants
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[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−2−q−3 + q−4−q−5 |
| HOMFLY-PT polynomial (db, data sources) | −z2a4−2a4 + z4a2 + 4z2a2 + 4a2−z2−1 |
| 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 | −q16−q14−q12 + 2q8 + 2q6 + 2q4 + q2−q−4 |
| The G2 invariant | q80 + q76−q74−2q68 + q66−q64−q62−q60−2q58−3q52−q50−q48 + q44−2q42 + q40 + q38 + 2q36 + q34 + 2q30 + 2q28 + 3q26 + 2q22 + 3q20 + q18 + q16 + q14 + 3q10−2q6 + q4 + 1−q−2−2q−4−q−12−q−14−q−20 + q−24 |
A1 Invariants.
| Weight | Invariant |
|---|---|
| 1 | −q11 + q5 + q3 + q + q−1−q−3 |
| 2 | q32−q28−q22−q20 + q12 + q10 + q6 + q4 + q2 + q−2−q−6 |
| 3 | −q63 + q59 + q57−q53 + q49 + q47−q43−q41−q35−2q33 + q29 + q27−q25 + q21−q17 + q15 + q13 + q5 + 2q3 + 2q + 2q−7−q−9−2q−11−q−13 + q−17 |
| 4 | q104−q100−q98−q96 + q94 + q92 + q90−2q86−q84 + q80 + 2q78 + q76−q72−q70 + q68 + 2q66 + q64−q62−3q60−2q58 + 2q54 + q52−2q50−2q48 + 2q44 + 2q42−q40−2q38 + q34 + q32−q30−q28−q20−q18 + q16 + q14 + q12 + q10 + q8 + q4 + 3q2 + 4 + 2q−2−q−4−4q−6−2q−8 + 3q−10 + 2q−12−q−14−4q−16−3q−18 + q−20 + 2q−22 + 2q−24−q−28 |
| 5 | −q155 + q151 + q149 + q147−q143−2q141−q139 + q135 + 2q133 + 2q131−2q127−2q125−2q123−q121 + q119 + 2q117 + 2q115 + q113−q111−3q109−2q107 + 3q103 + 4q101 + 3q99−3q95−4q93−2q91 + 2q89 + 4q87 + 3q85−q83−4q81−5q79−2q77 + 3q75 + 4q73 + 2q71−q69−4q67−2q65 + q63 + 4q61 + 3q59−3q55−3q53 + 2q49 + 2q47−3q43−2q41 + q37−2q33−2q31 + q27 + q25 + q15 + 2q13 + 3q11 + 3q9 + 2q7−q5−2q3 + 3q−1 + 5q−3 + 5q−5−q−7−7q−9−7q−11−2q−13 + 3q−15 + 7q−17 + 3q−19−3q−21−6q−23−4q−25 + q−27 + 3q−29 + 3q−31 + q−33−q−35−q−37 |
| 6 | q216−q212−q210−q208 + 2q202 + 2q200 + q198−q194−2q192−3q190−q188 + 2q184 + 3q182 + 3q180 + 2q178−q176−2q174−3q172−3q170−2q168 + 3q164 + 4q162 + 3q160 + q158−2q156−5q154−6q152−3q150 + q148 + 4q146 + 6q144 + 6q142 + 2q140−4q138−6q136−6q134−3q132 + 3q130 + 8q128 + 8q126 + 4q124−q122−7q120−9q118−5q116 + q114 + 6q112 + 7q110 + 5q108−2q106−8q104−8q102−4q100 + 2q98 + 7q96 + 9q94 + 4q92−3q90−7q88−6q86−q84 + 4q82 + 8q80 + 5q78−2q76−6q74−5q72−q70 + 3q68 + 6q66 + 3q64−3q62−5q60−4q58−q56 + 2q54 + 2q52−3q48−2q46 + q42 + q40−q36−2q34−q32 + q30 + 2q28 + 2q26 + 2q24 + q22−q18−2q16−q14 + q12 + 4q10 + 6q8 + 6q6 + 2q4−3q2−6−5q−2−2q−4 + 6q−6 + 11q−8 + 9q−10 + q−12−8q−14−12q−16−13q−18−2q−20 + 10q−22 + 12q−24 + 7q−26−q−28−7q−30−11q−32−6q−34 + q−36 + 5q−38 + 5q−40 + 4q−42 + 2q−44−2q−46−q−48−q−50−q−52−q−54 + q−58 |
A2 Invariants.
| Weight | Invariant |
|---|---|
| 1,0 | −q16−q14−q12 + 2q8 + 2q6 + 2q4 + q2−q−4 |
| 1,1 | q44 + 2q40−2q38 + 2q36−2q34−2q30−4q28−4q24 + 2q22−3q20 + 4q18 + 4q14 + q12 + 2q10 + 4q8 + 5q4 + 2−q−4−2q−6−2q−8 + q−12 |
| 2,0 | q42 + q40 + q38−q32−2q30−4q28−4q26−3q24−q22 + 2q20 + 3q18 + 5q16 + 3q14 + 3q12 + q10 + q8 + q4−q−8 |
A3 Invariants.
| Weight | Invariant |
|---|---|
| 0,1,0 | q34 + q30−q26−2q24−4q22−4q20−3q18 + 2q14 + 6q12 + 6q10 + 6q8 + 3q6 + q4−q2−2−2q−2−q−4−q−6 + q−10 |
| 1,0,0 | −q21−q19−2q17−q15 + 2q11 + 3q9 + 3q7 + 2q5 + q3−q−1−q−5 |
| 1,0,1 | q56 + 2q52 + q48−q44 + q42−2q40 + q38−4q36−2q34−6q32−5q30−5q28−6q26−2q22 + 6q20 + 5q18 + 10q16 + 9q14 + 9q12 + 8q10 + 2q8 + 3q6−2q4−3−q−2−q−4−2q−6−q−8−q−10 + q−16 |
A4 Invariants.
| Weight | Invariant |
|---|---|
| 0,1,0,0 | q44 + q42 + 2q40 + 2q38 + q36−q34−3q32−6q30−9q28−9q26−7q24−3q22 + q20 + 8q18 + 12q16 + 13q14 + 12q12 + 9q10 + 3q8−q6−4q4−5q2−5−3q−2−q−4 + q−10 + q−12 |
| 1,0,0,0 | −q26−q24−2q22−2q20−q18 + 2q14 + 3q12 + 4q10 + 3q8 + 2q6 + q4−1−q−2−q−6 |
B2 Invariants.
| Weight | Invariant |
|---|---|
| 0,1 | −q34−q30−q26 + q18 + 2q14 + 2q10 + q6 + q4 + q2 + q−4−q−6−q−10 |
| 1,0 | q56 + q48−q44−q42−q38−2q36−2q34−2q32−q30−q28 + 2q22 + 2q20 + 3q18 + 2q16 + 3q14 + 3q12 + 2q10 + q6−1−q−2−q−4−q−8−q−10 + q−16 |
D4 Invariants.
| Weight | Invariant |
|---|---|
| 1,0,0,0 | q46 + q42 + q38−q36−2q34−3q32−4q30−4q28−4q26−2q24−q22 + 3q20 + 4q18 + 7q16 + 6q14 + 7q12 + 4q10 + 3q8 + q6−q4−2q2−2−2q−2−2q−4−q−8 + q−14 |
G2 Invariants.
| Weight | Invariant |
|---|---|
| 1,0 | q80 + q76−q74−2q68 + q66−q64−q62−q60−2q58−3q52−q50−q48 + q44−2q42 + q40 + q38 + 2q36 + q34 + 2q30 + 2q28 + 3q26 + 2q22 + 3q20 + q18 + q16 + q14 + 3q10−2q6 + q4 + 1−q−2−2q−4−q−12−q−14−q−20 + q−24 |
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KnotTheory`, as shown in the (simulated) Mathematica session below. Your input (in red) is realistic; all else should have the same content as in a real mathematica session, but with different formatting. This Mathematica session is also available (albeit only for the knot 5_2) as the notebook PolynomialInvariantsSession.nb.
(The path below may be different on your system, and possibly also the KnotTheory` date)
In[1]:=
| AppendTo[$Path, "C:/drorbn/projects/KAtlas/"];
<< KnotTheory`
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Loading KnotTheory` version of August 31, 2006, 11:25:27.5625.
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In[3]:=
| K = Knot["8 20"];
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In[4]:=
| Alexander[K][t]
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KnotTheory::loading: Loading precomputed data in PD4Knots`.
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Out[4]=
| t2−2t + 3−2t−1 + t−2 |
In[5]:=
| Conway[K][z]
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Out[5]=
| z4 + 2z2 + 1 |
In[6]:=
| Alexander[K, 2][t]
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KnotTheory::credits: The program Alexander[K, r] to compute Alexander ideals was written by Jana Archibald at the University of Toronto in the summer of 2005.
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Out[6]=
| {1} |
In[7]:=
| {KnotDet[K], KnotSignature[K]}
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Out[7]=
| { 9, 0 } |
In[8]:=
| Jones[K][q]
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KnotTheory::loading: Loading precomputed data in Jones4Knots`.
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Out[8]=
| −q + 2−q−1 + 2q−2−q−3 + q−4−q−5 |
In[9]:=
| HOMFLYPT[K][a, z]
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KnotTheory::credits: The HOMFLYPT program was written by Scott Morrison.
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Out[9]=
| −z2a4−2a4 + z4a2 + 4z2a2 + 4a2−z2−1 |
In[10]:=
| Kauffman[K][a, z]
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KnotTheory::loading: Loading precomputed data in Kauffman4Knots`.
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Out[10]=
| a4z6 + a2z6 + a5z5 + 2a3z5 + az5−4a4z4−4a2z4−4a5z3−7a3z3−3az3 + 4a4z2 + 6a2z2 + 2z2 + 3a5z + 5a3z + 3az + za−1−2a4−4a2−1 |
[edit] "Similar" Knots (within the Atlas)
Same Alexander/Conway Polynomial: {10_140, K11n73, K11n74,}
Same Jones Polynomial (up to mirroring,
):
{}
KnotTheory`. Your input (in red) is realistic; all else should have the same content as in a real mathematica session, but with different formatting.
(The path below may be different on your system, and possibly also the KnotTheory` date)
In[1]:=
| AppendTo[$Path, "C:/drorbn/projects/KAtlas/"];
<< KnotTheory`
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Loading KnotTheory` version of May 31, 2006, 14:15:20.091.
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In[3]:=
| K = Knot["8 20"];
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In[4]:=
| {A = Alexander[K][t], J = Jones[K][q]}
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KnotTheory::loading: Loading precomputed data in PD4Knots`.
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KnotTheory::loading: Loading precomputed data in Jones4Knots`.
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Out[4]=
| { t2−2t + 3−2t−1 + t−2, −q + 2−q−1 + 2q−2−q−3 + q−4−q−5 } |
In[5]:=
| DeleteCases[Select[AllKnots[], (A === Alexander[#][t]) &], K]
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KnotTheory::loading: Loading precomputed data in DTCode4KnotsTo11`.
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KnotTheory::credits: The GaussCode to PD conversion was written by Siddarth Sankaran at the University of Toronto in the summer of 2005.
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Out[5]=
| {10_140, K11n73, K11n74,} |
In[6]:=
| DeleteCases[
Select[
AllKnots[],
(J === Jones[#][q] || (J /. q -> 1/q) === Jones[#][q]) &
],
K
]
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KnotTheory::loading: Loading precomputed data in Jones4Knots11`.
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Out[6]=
| {} |
[edit] Vassiliev invariants
| V2 and V3: | (2, -2) |
| V2,1 through V6,9: |
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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. |
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| Integral Khovanov Homology
(db, data source) |
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[edit] The Coloured Jones Polynomials
| n | Jn |
| 2 | −q2 + q + 1−2q−1 + 2q−2 + q−3−2q−4 + q−5 + 2q−6−2q−7 + 2q−9−2q−10−q−11 + 2q−12−q−13−q−14 + q−15 |
| 3 | q7−q6−q5−q4 + 2q3 + 2q2−3q−1 + 2q−1 + 4q−2−3q−3−2q−4 + q−5 + 4q−6−3q−7−q−8 + q−9 + 2q−10−2q−11 + q−14−q−17−q−18 + q−19 + q−20−q−21−2q−22 + q−23 + 2q−24−2q−26 + q−28 + q−29−q−30 |
| 4 | −q12 + q11 + 2q10−q8−5q7 + 5q5 + 3q4−10q2−2q + 8 + 6q−1 + 2q−2−11q−3−4q−4 + 7q−5 + 7q−6 + 2q−7−11q−8−4q−9 + 7q−10 + 5q−11 + 2q−12−10q−13−4q−14 + 7q−15 + 4q−16 + 2q−17−8q−18−4q−19 + 6q−20 + 2q−21 + 3q−22−5q−23−4q−24 + 4q−25 + 3q−27−2q−28−3q−29 + 2q−30−2q−31 + 2q−32−q−34 + 3q−35−3q−36 + 4q−40−2q−41−q−42−q−43−q−44 + 3q−45−q−48−q−49 + q−50 |
| 5 | −q16 + 2q14 + 2q13−2q11−6q10−2q9 + 5q8 + 8q7 + 4q6−6q5−11q4−7q3 + 5q2 + 14q + 10−6q−1−13q−2−10q−3 + 3q−4 + 15q−5 + 13q−6−5q−7−13q−8−11q−9 + 2q−10 + 14q−11 + 13q−12−5q−13−13q−14−10q−15 + 2q−16 + 13q−17 + 11q−18−5q−19−11q−20−9q−21 + q−22 + 11q−23 + 10q−24−2q−25−9q−26−9q−27−q−28 + 8q−29 + 10q−30 + q−31−6q−32−8q−33−4q−34 + 5q−35 + 8q−36 + 4q−37−3q−38−6q−39−5q−40 + 5q−42 + 5q−43−2q−45−4q−46−2q−47 + q−48 + 3q−49 + q−50 + q−51−q−52−q−53−q−56 + q−58 + q−59 + q−60−2q−62−2q−63 + q−65 + q−66 + 2q−67−2q−69−q−70 + q−73 + q−74−q−75 |
| 6 | q26−q25−q24−q20 + 5q19 + q18−4q15−7q14−6q13 + 9q12 + 7q11 + 8q10 + 5q9−6q8−19q7−17q6 + 10q5 + 11q4 + 17q3 + 13q2−4q−24−25q−1 + 7q−2 + 10q−3 + 20q−4 + 18q−5−24q−7−27q−8 + 4q−9 + 8q−10 + 19q−11 + 19q−12 + q−13−23q−14−26q−15 + 4q−16 + 8q−17 + 18q−18 + 17q−19−22q−21−25q−22 + 5q−23 + 8q−24 + 17q−25 + 15q−26−q−27−19q−28−23q−29 + 5q−30 + 5q−31 + 14q−32 + 14q−33 + q−34−13q−35−20q−36 + 2q−37 + q−38 + 10q−39 + 13q−40 + 5q−41−6q−42−17q−43−2q−44−4q−45 + 5q−46 + 12q−47 + 9q−48 + q−49−12q−50−4q−51−9q−52−q−53 + 8q−54 + 9q−55 + 7q−56−5q−57−2q−58−10q−59−6q−60 + 2q−61 + 5q−62 + 9q−63 + q−64 + 3q−65−6q−66−6q−67−3q−68−q−69 + 6q−70 + q−71 + 5q−72−2q−74−3q−75−3q−76 + 3q−77−3q−78 + 2q−79 + q−80 + q−81−q−83 + 4q−84−4q−85−q−86−q−87 + 5q−91−q−92−q−94−q−95−2q−96−q−97 + 3q−98 + q−100−q−103−q−104 + q−105 |
| 7 | −q35 + q34 + q33 + q32−2q30−q29−2q28−3q27 + 4q25 + 6q24 + 7q23−q21−7q20−14q19−10q18 + 11q16 + 21q15 + 16q14 + 6q13−9q12−28q11−26q10−16q9 + 6q8 + 34q7 + 35q6 + 21q5−3q4−33q3−38q2−30q−3 + 34q−1 + 44q−2 + 31q−3 + 6q−4−31q−5−39q−6−35q−7−10q−8 + 30q−9 + 42q−10 + 32q−11 + 10q−12−28q−13−38q−14−34q−15−11q−16 + 29q−17 + 40q−18 + 31q−19 + 9q−20−28q−21−38q−22−33q−23−9q−24 + 30q−25 + 40q−26 + 30q−27 + 6q−28−28q−29−37q−30−31q−31−7q−32 + 28q−33 + 38q−34 + 27q−35 + 5q−36−24q−37−34q−38−28q−39−7q−40 + 23q−41 + 33q−42 + 24q−43 + 6q−44−17q−45−28q−46−25q−47−9q−48 + 14q−49 + 26q−50 + 22q−51 + 10q−52−8q−53−20q−54−21q−55−13q−56 + 3q−57 + 16q−58 + 19q−59 + 13q−60 + 3q−61−10q−62−15q−63−14q−64−8q−65 + 4q−66 + 11q−67 + 14q−68 + 11q−69−5q−71−10q−72−13q−73−7q−74 + 7q−76 + 13q−77 + 6q−78 + 6q−79−10q−81−9q−82−8q−83−3q−84 + 5q−85 + 5q−86 + 10q−87 + 9q−88−2q−89−3q−90−6q−91−9q−92−3q−93−3q−94 + 5q−95 + 9q−96 + 2q−97 + 4q−98 + q−99−5q−100−3q−101−6q−102−2q−103 + 4q−104−q−105 + 3q−106 + 3q−107 + 2q−109−2q−110−2q−111 + 2q−112−3q−113−q−114−2q−116 + 3q−117 + q−118 + 3q−120−q−123−4q−124−q−127 + 2q−128 + q−129 + 2q−130 + q−131−2q−132−q−133−q−135 + q−138 + q−139−q−140 |
[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. |
|



