3 1
From Knot Atlas
|
|
|
|
![]() (KnotPlot image) |
See the full Rolfsen Knot Table. Visit 3 1's page at the Knot Server (KnotPlot driven, includes 3D interactive images!) Visit 3_1's page at Knotilus! Visit 3 1's page at the original Knot Atlas! |
|
3_1 is also known as "The Trefoil Knot", after plants of the genus Trifolium, which have compound trifoliate leaves, and as the "Overhand Knot". See also T(3,2). |
The trefoil is perhaps the easiest knot to find in "nature", and is topologically equivalent to the interlaced form of the common Christian and pagan "triquetra" symbol [12]:
Logo of Caixa Geral de Depositos, Lisboa [1] | A knot consists of two harts in Kolam [2] | Thurston's Trefoil - Figure Eight Trick [3] |
A Knotted Box [4] | A trefoil near the Hollander York Gallery [5] | A Knotted Pencil [6] | The NeverEnding Story is a connected sum of two trefoils. [7] |
Banco Do Brasil [8] | A hagfish tying itself in a knot to escape capture. [9] | A Kenyan Stone [10] | |
Mike Hutchings' Rope Trick [11] |
[edit] Non-prime (compound) versions
For a configuration of two trefoils along a closed loop which is prime, see 10_120.
[edit] Knot presentations
| Planar diagram presentation | X1425 X3641 X5263 |
| Gauss code | -1, 3, -2, 1, -3, 2 |
| Dowker-Thistlethwaite code | 4 6 2 |
| Conway Notation | [3] |
| Minimum Braid Representative | A Morse Link Presentation | An Arc Presentation | ||
Length is 3, width is 2, Braid index is 2 |
| ![]() [{5, 2}, {1, 3}, {2, 4}, {3, 5}, {4, 1}] |
[edit Notes on presentations of 3 1]
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[$Path, "C:/drorbn/projects/KAtlas/"];
<< KnotTheory`
|
Loading KnotTheory` version of May 31, 2006, 14:15:20.091.
|
In[3]:=
| K = Knot["3 1"];
|
In[4]:=
| PD[K]
|
KnotTheory::loading: Loading precomputed data in PD4Knots`.
|
Out[4]=
| X1425 X3641 X5263 |
In[5]:=
| GaussCode[K]
|
Out[5]=
| -1, 3, -2, 1, -3, 2 |
In[6]:=
| DTCode[K]
|
Out[6]=
| 4 6 2 |
(The path below may be different on your system)
In[7]:=
| AppendTo[$Path, "C:/bin/LinKnot/"];
|
In[8]:=
| ConwayNotation[K]
|
Out[8]=
| [3] |
In[9]:=
| br = BR[K]
|
KnotTheory::credits: The minimum braids representing the knots with up to 10 crossings were provided by Thomas Gittings. See arXiv:math.GT/0401051.
|
Out[9]=
| BR(2,{−1,−1,−1}) |
In[10]:=
| {First[br], Crossings[br], BraidIndex[K]}
|
KnotTheory::credits: The braid index data known to KnotTheory` is taken from Charles Livingston's http://www.indiana.edu/~knotinfo/.
|
KnotTheory::loading: Loading precomputed data in IndianaData`.
|
Out[10]=
| { 2, 3, 2 } |
In[11]:=
| Show[BraidPlot[br]]
|
Out[11]=
| -Graphics- |
In[12]:=
| Show[DrawMorseLink[K]]
|
KnotTheory::credits: "MorseLink was added to KnotTheory` by Siddarth Sankaran at the University of Toronto in the summer of 2005."
|
KnotTheory::credits: "DrawMorseLink was written by Siddarth Sankaran at the University of Toronto in the summer of 2005."
|
|
Out[12]=
| -Graphics- |
In[13]:=
| ap = ArcPresentation[K]
|
Out[13]=
| ArcPresentation[{5, 2}, {1, 3}, {2, 4}, {3, 5}, {4, 1}] |
In[14]:=
| Draw[ap]
|
|
Out[14]=
| -Graphics- |
[edit] Three dimensional invariants
|
[edit Notes for 3 1's three dimensional invariants] The rope length of the trefoil is known to be no more than 16.372, by numerical experiments, while the sharpest known lower bound (actually applicable to all non-trivial knots) is 15.66. The trefoil is a fibered knot! A java applet demonstrating it, written by Robert Barrington Leigh at the University of Toronto, is here. |
[edit] Four dimensional invariants
|
[edit] Polynomial invariants
| Alexander polynomial | t−1 + t−1 |
| Conway polynomial | z2 + 1 |
| 2nd Alexander ideal (db, data sources) | {1} |
| Determinant and Signature | { 3, -2 } |
| Jones polynomial | q−1 + q−3−q−4 |
| HOMFLY-PT polynomial (db, data sources) | −a4 + z2a2 + 2a2 |
| Kauffman polynomial (db, data sources) | za5 + z2a4−a4 + za3 + z2a2−2a2 |
| The A2 invariant | −q14−q12 + q8 + 2q6 + q4 + q2 |
| The G2 invariant | q72−q64−q62−q56−2q54−q52 + q50−q46−2q44 + 2q40 + q38−q36 + 2q32 + 2q30 + q28 + 2q22 + 2q20 + q14 + q12 + q10 |
The braid index of 3_1 is only 2, so it's easy to calculate lots of quantum invariants. A1 Invariants.
| Weight | Invariant |
|---|---|
| 1 | −q9 + q5 + q3 + q |
| 2 | q24−q20−q18−q16 + q10 + q8 + q6 + q4 + q2 |
| 3 | −q45 + q41 + q39 + q37−q31−q29−q27−q25−q23 + q15 + q13 + q11 + q9 + q7 + q5 + q3 |
| 4 | q72−q68−q66−q64 + q58 + q56 + q54 + q52 + q50−q42−q40−q38−q36−q34−q32−q30 + q20 + q18 + q16 + q14 + q12 + q10 + q8 + q6 + q4 |
| 5 | −q105 + q101 + q99 + q97−q91−q89−q87−q85−q83 + q75 + q73 + q71 + q69 + q67 + q65 + q63−q53−q51−q49−q47−q45−q43−q41−q39−q37 + q25 + q23 + q21 + q19 + q17 + q15 + q13 + q11 + q9 + q7 + q5 |
| 6 | q144−q140−q138−q136 + q130 + q128 + q126 + q124 + q122−q114−q112−q110−q108−q106−q104−q102 + q92 + q90 + q88 + q86 + q84 + q82 + q80 + q78 + q76−q64−q62−q60−q58−q56−q54−q52−q50−q48−q46−q44 + q30 + q28 + q26 + q24 + q22 + q20 + q18 + q16 + q14 + q12 + q10 + q8 + q6 |
| 8 | q240−q236−q234−q232 + q226 + q224 + q222 + q220 + q218−q210−q208−q206−q204−q202−q200−q198 + q188 + q186 + q184 + q182 + q180 + q178 + q176 + q174 + q172−q160−q158−q156−q154−q152−q150−q148−q146−q144−q142−q140 + q126 + q124 + q122 + q120 + q118 + q116 + q114 + q112 + q110 + q108 + q106 + q104 + q102−q86−q84−q82−q80−q78−q76−q74−q72−q70−q68−q66−q64−q62−q60−q58 + q40 + q38 + q36 + q34 + q32 + q30 + q28 + q26 + q24 + q22 + q20 + q18 + q16 + q14 + q12 + q10 + q8 |
A2 Invariants.
| Weight | Invariant |
|---|---|
| 0,1 | −q14−q12 + q8 + 2q6 + q4 + q2 |
| 0,2 | q34 + q32 + q30−q28−2q26−3q24−3q22−q20 + 2q16 + 2q14 + 3q12 + 2q10 + 2q8 + q6 + q4 |
| 1,0 | −q14−q12 + q8 + 2q6 + q4 + q2 |
| 1,1 | q36−2q24−2q22−3q20−2q18 + 2q14 + 3q12 + 4q10 + 4q8 + 2q6 + q4 |
| 2,0 | q34 + q32 + q30−q28−2q26−3q24−3q22−q20 + 2q16 + 2q14 + 3q12 + 2q10 + 2q8 + q6 + q4 |
| 3,0 | −q60−q58−q56 + 2q52 + 3q50 + 4q48 + 3q46 + 2q44−q42−3q40−5q38−5q36−5q34−4q32−2q30−q28 + q26 + 2q24 + 3q22 + 3q20 + 4q18 + 3q16 + 3q14 + 2q12 + 2q10 + q8 + q6 |
A3 Invariants.
| Weight | Invariant |
|---|---|
| 0,0,1 | −q19−q17−q15 + q11 + 2q9 + 2q7 + q5 + q3 |
| 0,1,0 | q30−q24−2q22−2q20−2q18 + q14 + 3q12 + 3q10 + 3q8 + q6 + q4 |
| 1,0,0 | −q19−q17−q15 + q11 + 2q9 + 2q7 + q5 + q3 |
| 1,0,1 | q48 + q38 + q36 + q34−q32−3q30−5q28−6q26−6q24−3q22 + q20 + 4q18 + 7q16 + 8q14 + 7q12 + 5q10 + 2q8 + q6 |
A4 Invariants.
| Weight | Invariant |
|---|---|
| 0,0,0,1 | −q24−q22−q20−q18 + q14 + 2q12 + 2q10 + 2q8 + q6 + q4 |
| 0,1,0,0 | q40 + q38 + q36−q32−3q30−4q28−4q26−3q24−q22 + q20 + 4q18 + 4q16 + 5q14 + 4q12 + 3q10 + q8 + q6 |
| 1,0,0,0 | −q24−q22−q20−q18 + q14 + 2q12 + 2q10 + 2q8 + q6 + q4 |
A5 Invariants.
| Weight | Invariant |
|---|---|
| 0,0,0,0,1 | −q29−q27−q25−q23−q21 + q17 + 2q15 + 2q13 + 2q11 + 2q9 + q7 + q5 |
| 1,0,0,0,0 | −q29−q27−q25−q23−q21 + q17 + 2q15 + 2q13 + 2q11 + 2q9 + q7 + q5 |
A6 Invariants.
| Weight | Invariant |
|---|---|
| 0,0,0,0,0,1 | −q34−q32−q30−q28−q26−q24 + q20 + 2q18 + 2q16 + 2q14 + 2q12 + 2q10 + q8 + q6 |
| 1,0,0,0,0,0 | −q34−q32−q30−q28−q26−q24 + q20 + 2q18 + 2q16 + 2q14 + 2q12 + 2q10 + q8 + q6 |
B2 Invariants.
| Weight | Invariant |
|---|---|
| 0,1 | −q30−q24 + q14 + q12 + q10 + q8 + q6 + q4 |
| 1,0 | q48−q38−q36−q34−q32−q30−q28 + q22 + q20 + 2q18 + q16 + 2q14 + q12 + q10 + q6 |
B3 Invariants.
| Weight | Invariant |
|---|---|
| 1,0,0 | q72−q58−q54−q52−q50−q48−q46−q44−q42 + q34 + 2q30 + q28 + 2q26 + q24 + 2q22 + q20 + 2q18 + q14 + q10 |
B4 Invariants.
| Weight | Invariant |
|---|---|
| 1,0,0,0 | q96−q78−q74−q70−q68−q66−q64−q62−q60−q58−q54 + q46 + 2q42 + 2q38 + q36 + 2q34 + q32 + 2q30 + q28 + 2q26 + 2q22 + q18 + q14 |
B5 Invariants.
| Weight | Invariant |
|---|---|
| 1,0,0,0,0 | q120−q98−q94−q90−q86−q84−q82−q80−q78−q76−q74−q70−q66 + q58 + 2q54 + 2q50 + 2q46 + q44 + 2q42 + q40 + 2q38 + q36 + 2q34 + 2q30 + 2q26 + q22 + q18 |
C3 Invariants.
| Weight | Invariant |
|---|---|
| 1,0,0 | −q42−q34−q32−q24 + q20 + 2q18 + q16 + q14 + q12 + 2q10 + q8 + q6 |
C4 Invariants.
| Weight | Invariant |
|---|---|
| 1,0,0,0 | −q54−q44−q42−q40−q32−q30 + q26 + 2q24 + 2q22 + q20 + q18 + q16 + 2q14 + 2q12 + q10 + q8 |
D4 Invariants.
| Weight | Invariant |
|---|---|
| 0,1,0,0 | q72−q64−q62 + 2q56 + 4q54 + 5q52 + 4q50 + 3q48−q46−5q44−9q42−13q40−14q38−13q36−9q34−4q32 + 2q30 + 7q28 + 12q26 + 12q24 + 14q22 + 11q20 + 9q18 + 6q16 + 4q14 + q12 + q10 |
| 1,0,0,0 | q42−q34−q32−2q30−2q28−2q26−q24 + q20 + 2q18 + 3q16 + 3q14 + 3q12 + 2q10 + q8 + q6 |
G2 Invariants.
| Weight | Invariant |
|---|---|
| 0,1 | q144−q126 + q122−q116 + 2q112 + q110−q108 + 2q104 + q102−q98−q96 + q94−2q90−2q88−q86−q84−2q82−3q80−2q78−2q76−2q74−2q72−2q70−q68−q64−q62 + q60 + q58 + q56 + 2q54 + q52 + 2q50 + 3q48 + 2q46 + 2q44 + 3q42 + 2q40 + 2q38 + 3q36 + 2q34 + q32 + 2q30 + q28 + q26 + q24 + q18 |
| 1,0 | q72−q64−q62−q56−2q54−q52 + q50−q46−2q44 + 2q40 + q38−q36 + 2q32 + 2q30 + q28 + 2q22 + 2q20 + q14 + q12 + q10 |
.
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[$Path, "C:/drorbn/projects/KAtlas/"];
<< KnotTheory`
|
Loading KnotTheory` version of August 31, 2006, 11:25:27.5625.
|
In[3]:=
| K = Knot["3 1"];
|
In[4]:=
| Alexander[K][t]
|
KnotTheory::loading: Loading precomputed data in PD4Knots`.
|
Out[4]=
| t−1 + t−1 |
In[5]:=
| Conway[K][z]
|
Out[5]=
| z2 + 1 |
In[6]:=
| Alexander[K, 2][t]
|
KnotTheory::credits: The program Alexander[K, r] to compute Alexander ideals was written by Jana Archibald at the University of Toronto in the summer of 2005.
|
Out[6]=
| {1} |
In[7]:=
| {KnotDet[K], KnotSignature[K]}
|
Out[7]=
| { 3, -2 } |
In[8]:=
| Jones[K][q]
|
KnotTheory::loading: Loading precomputed data in Jones4Knots`.
|
Out[8]=
| q−1 + q−3−q−4 |
In[9]:=
| HOMFLYPT[K][a, z]
|
KnotTheory::credits: The HOMFLYPT program was written by Scott Morrison.
|
Out[9]=
| −a4 + z2a2 + 2a2 |
In[10]:=
| Kauffman[K][a, z]
|
KnotTheory::loading: Loading precomputed data in Kauffman4Knots`.
|
Out[10]=
| za5 + z2a4−a4 + za3 + z2a2−2a2 |
[edit] "Similar" Knots (within the Atlas)
Same Alexander/Conway Polynomial: {}
Same Jones Polynomial (up to mirroring,
):
{}
KnotTheory`. Your input (in red) is realistic; all else should have the same content as in a real mathematica session, but with different formatting.
(The path below may be different on your system, and possibly also the KnotTheory` date)
In[1]:=
| AppendTo[$Path, "C:/drorbn/projects/KAtlas/"];
<< KnotTheory`
|
Loading KnotTheory` version of May 31, 2006, 14:15:20.091.
|
In[3]:=
| K = Knot["3 1"];
|
In[4]:=
| {A = Alexander[K][t], J = Jones[K][q]}
|
KnotTheory::loading: Loading precomputed data in PD4Knots`.
|
KnotTheory::loading: Loading precomputed data in Jones4Knots`.
|
Out[4]=
| { t−1 + t−1, q−1 + q−3−q−4 } |
In[5]:=
| DeleteCases[Select[AllKnots[], (A === Alexander[#][t]) &], K]
|
KnotTheory::loading: Loading precomputed data in DTCode4KnotsTo11`.
|
KnotTheory::credits: The GaussCode to PD conversion was written by Siddarth Sankaran at the University of Toronto in the summer of 2005.
|
Out[5]=
| {} |
In[6]:=
| DeleteCases[
Select[
AllKnots[],
(J === Jones[#][q] || (J /. q -> 1/q) === Jones[#][q]) &
],
K
]
|
KnotTheory::loading: Loading precomputed data in Jones4Knots11`.
|
Out[6]=
| {} |
[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 = -2 is the signature of 3 1. Nonzero entries off the critical diagonals (if any exist) are highlighted in red. |
|
| Integral Khovanov Homology
(db, data source) |
|
[edit] The Coloured Jones Polynomials
| n | Jn |
| 2 | q−2 + q−5−q−7 + q−8−q−9−q−10 + q−11 |
| 3 | q−3 + q−7−q−10 + q−11−q−13−q−14 + q−15−q−17 + q−19 + q−20−q−21 |
| 4 | q−4 + q−9−q−13 + q−14−q−17−q−18 + q−19−q−22−q−23 + 2q−24−q−28 + 2q−29−q−32−q−33 + q−34 |
| 5 | q−5 + q−11−q−16 + q−17−q−21−q−22 + q−23−q−27−q−28 + q−29 + q−30−q−33 + q−35 + q−36−q−39 + q−42−q−44−q−45 + q−48 + q−49−q−50 |
| 6 | q−6 + q−13−q−19 + q−20−q−25−q−26 + q−27−q−32−q−33 + q−34 + q−36−q−39−q−40 + 2q−41 + q−43−q−46−q−47 + 2q−48−q−53−2q−54 + 2q−55−q−60−q−61 + 2q−62 + q−64−q−67−q−68 + q−69 |
| 7 | q−7 + q−15−q−22 + q−23−q−29−q−30 + q−31−q−37−q−38 + q−39 + q−42−q−45−q−46 + q−47 + q−48 + q−50−q−53−q−54 + q−55 + q−56 + q−58−q−59−q−61−q−62 + q−63 + q−66−q−67−q−69−q−70 + q−71 + q−73 + q−74−q−75−q−78 + q−79 + q−81 + q−82−q−83−q−84−q−86 + q−89 + q−90−q−91 |
[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. |
|

![Thurston's Trefoil - Figure Eight Trick [3]](/w/images/7/74/DylansTrefoil_120.jpg)
![The NeverEnding Story is a connected sum of two trefoils. [7]](/w/images/5/55/Auryn_120.gif)


