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]
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A knot consists of two harts in Kolam [2]
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A basic form of the interlaced Triquetra; as a Christian symbol, it refers to the Trinity
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Further images...
Trefoil/triquetra without outside corners (made from straight lines and 240° circular arcs)
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Triquetra made from circular arc ribbons
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A trefoil near the Hollander York Gallery [4]
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Trefoil of three intersecting circles
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Trefoil depicted in non-threefold form
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3D depiction in non-threefold form
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A hagfish tying itself in a knot to escape capture. [5]
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One version of the Germanic "Valknut" symbol
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In the form of an architectural trefoil
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Alternate Valknut depiction
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Simple overhand knot of practical knot-tying
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Tightly folded pentagonal overhand knot
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Visually fancier square trefoil
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Trefoil knot as impossible object
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Logo of the Caixa Geral de Depósitos with white background
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The NeverEnding Story logo is a connected sum of two trefoils. [7]
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Mike Hutchings' Rope Trick [8]
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Thurston's Trefoil - Figure Eight Trick [9]
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Non-prime (compound) versions
Two trefoils (single-closed-loop version of the "granny knot" of practical knot-tying).
Two trefoils (single-closed-loop version of the "square knot" of practical knot-tying)
Three trefoils (symmetrical).
Four trefoils (Celtic or pseudo-Celtic decorative knot which fits in square)
Three trefoils along a closed loop which itself is knotted as a trefoil.
Sum of four trefoils, Multan, Pakistan
For configurations of two trefoils along a closed loop which are prime, see 8_15 and 10_120. For a configuration of three trefoils along a closed loop which is prime, see K13a248. For a prime link consisting of two joined trefoils, see L10a108.
Knot presentations
Four dimensional invariants
Polynomial invariants
Further Quantum Invariants
Further quantum knot invariants for 3_1.
The braid index of 3_1 is only 2, so it's easy to calculate lots of quantum invariants.
A1 Invariants.
Weight
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Invariant
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1
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2
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3
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4
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5
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6
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8
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A2 Invariants.
Weight
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Invariant
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0,1
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0,2
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1,0
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1,1
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2,0
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3,0
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A3 Invariants.
Weight
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Invariant
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0,0,1
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0,1,0
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1,0,0
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1,0,1
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A4 Invariants.
Weight
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Invariant
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0,0,0,1
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0,1,0,0
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1,0,0,0
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A5 Invariants.
Weight
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Invariant
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0,0,0,0,1
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1,0,0,0,0
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A6 Invariants.
Weight
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Invariant
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0,0,0,0,0,1
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1,0,0,0,0,0
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B2 Invariants.
Weight
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Invariant
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0,1
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1,0
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B3 Invariants.
Weight
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Invariant
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1,0,0
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B4 Invariants.
Weight
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Invariant
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1,0,0,0
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B5 Invariants.
Weight
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Invariant
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1,0,0,0,0
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C3 Invariants.
Weight
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Invariant
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1,0,0
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C4 Invariants.
Weight
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Invariant
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1,0,0,0
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D4 Invariants.
Weight
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Invariant
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0,1,0,0
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1,0,0,0
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G2 Invariants.
Weight
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Invariant
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0,1
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1,0
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.
Computer Talk
The above data is available with the
Mathematica package
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]:=
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AppendTo[$Path, "C:/drorbn/projects/KAtlas/"];
<< KnotTheory`
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KnotTheory::loading: Loading precomputed data in PD4Knots`.
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Out[4]=
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Out[5]=
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In[6]:=
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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]=
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In[7]:=
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{KnotDet[K], KnotSignature[K]}
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KnotTheory::loading: Loading precomputed data in Jones4Knots`.
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Out[8]=
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In[9]:=
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HOMFLYPT[K][a, z]
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KnotTheory::credits: The HOMFLYPT program was written by Scott Morrison.
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Out[9]=
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In[10]:=
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Kauffman[K][a, z]
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KnotTheory::loading: Loading precomputed data in Kauffman4Knots`.
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Out[10]=
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"Similar" Knots (within the Atlas)
Same Alexander/Conway Polynomial:
{...}
Same Jones Polynomial (up to mirroring, ):
{...}
V2,1 through V6,9:
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V2,1
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V3,1
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V4,1
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V4,2
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V4,3
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V5,1
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V5,2
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V5,3
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V5,4
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V6,1
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V6,2
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V6,3
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V6,4
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V6,5
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V6,6
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V6,7
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V6,8
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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.
The coefficients of the monomials are shown, along with their alternating sums (fixed , alternation over ). The squares with yellow highlighting are those on the "critical diagonals", where or , where -2 is the signature of 3 1. Nonzero entries off the critical diagonals (if any exist) are highlighted in red.
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-3 | -2 | -1 | 0 | χ |
-1 | | | | 1 | 1 |
-3 | | | | 1 | 1 |
-5 | | 1 | | | 1 |
-7 | | | | | 0 |
-9 | 1 | | | | -1 |
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The Coloured Jones Polynomials
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2
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3
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4
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5
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6
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7
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Computer Talk
Much of the above data can be recomputed by Mathematica using the package KnotTheory`
. See A Sample KnotTheory` Session.
In[1]:= |
<< KnotTheory` |
Loading KnotTheory` (version of August 29, 2005, 15:27:48)... |
In[2]:= | PD[Knot[3, 1]] |
Out[2]= | PD[X[1, 4, 2, 5], X[3, 6, 4, 1], X[5, 2, 6, 3]] |
In[3]:= | GaussCode[Knot[3, 1]] |
Out[3]= | GaussCode[-1, 3, -2, 1, -3, 2] |
In[4]:= | DTCode[Knot[3, 1]] |
Out[4]= | DTCode[4, 6, 2] |
In[5]:= | br = BR[Knot[3, 1]] |
Out[5]= | BR[2, {-1, -1, -1}] |
In[6]:= | {First[br], Crossings[br]} |
Out[6]= | {2, 3} |
In[7]:= | BraidIndex[Knot[3, 1]] |
Out[7]= | 2 |
In[8]:= | Show[DrawMorseLink[Knot[3, 1]]] |
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Out[8]= | -Graphics- |
In[9]:= | (#[Knot[3, 1]]&) /@ {SymmetryType, UnknottingNumber, ThreeGenus, BridgeIndex, SuperBridgeIndex, NakanishiIndex} |
Out[9]= | {Reversible, 1, 1, 2, 3, 1} |
In[10]:= | alex = Alexander[Knot[3, 1]][t] |
Out[10]= | 1
-1 + - + t
t |
In[11]:= | Conway[Knot[3, 1]][z] |
Out[11]= | 2
1 + z |
In[12]:= | Select[AllKnots[], (alex === Alexander[#][t])&] |
Out[12]= | {Knot[3, 1]} |
In[13]:= | {KnotDet[Knot[3, 1]], KnotSignature[Knot[3, 1]]} |
Out[13]= | {3, -2} |
In[14]:= | Jones[Knot[3, 1]][q] |
Out[14]= | -4 -3 1
-q + q + -
q |
In[15]:= | Select[AllKnots[], (J === Jones[#][q] || (J /. q-> 1/q) === Jones[#][q])&] |
Out[15]= | {Knot[3, 1]} |
In[16]:= | A2Invariant[Knot[3, 1]][q] |
Out[16]= | -14 -12 -8 2 -4 -2
-q - q + q + -- + q + q
6
q |
In[17]:= | HOMFLYPT[Knot[3, 1]][a, z] |
Out[17]= | 2 4 2 2
2 a - a + a z |
In[18]:= | Kauffman[Knot[3, 1]][a, z] |
Out[18]= | 2 4 3 5 2 2 4 2
-2 a - a + a z + a z + a z + a z |
In[19]:= | {Vassiliev[2][Knot[3, 1]], Vassiliev[3][Knot[3, 1]]} |
Out[19]= | {1, -1} |
In[20]:= | Kh[Knot[3, 1]][q, t] |
Out[20]= | -3 1 1 1
q + - + ----- + -----
q 9 3 5 2
q t q t |
In[21]:= | ColouredJones[Knot[3, 1], 2][q] |
Out[21]= | -11 -10 -9 -8 -7 -5 -2
q - q - q + q - q + q + q |