8 4
|
|
Visit 8 4's page at the Knot Server (KnotPlot driven, includes 3D interactive images!)
Visit 8 4's page at Knotilus! Visit 8 4's page at the original Knot Atlas! |
8 4 Quick Notes |
Knot presentations
Planar diagram presentation | X6271 X14,10,15,9 X10,3,11,4 X2,13,3,14 X12,5,13,6 X16,8,1,7 X4,11,5,12 X8,16,9,15 |
Gauss code | 1, -4, 3, -7, 5, -1, 6, -8, 2, -3, 7, -5, 4, -2, 8, -6 |
Dowker-Thistlethwaite code | 6 10 12 16 14 4 2 8 |
Conway Notation | [413] |
Three dimensional invariants
|
Four dimensional invariants
|
Polynomial invariants
A1 Invariants.
Weight | Invariant |
---|---|
1 | |
2 | |
3 | |
4 | |
5 | |
6 |
A2 Invariants.
Weight | Invariant |
---|---|
1,0 | |
1,1 | |
2,0 | |
3,0 |
A3 Invariants.
Weight | Invariant |
---|---|
0,1,0 | |
1,0,0 |
A4 Invariants.
Weight | Invariant |
---|---|
0,1,0,0 | |
1,0,0,0 |
B2 Invariants.
Weight | Invariant |
---|---|
0,1 | |
1,0 |
D4 Invariants.
Weight | Invariant |
---|---|
1,0,0,0 |
G2 Invariants.
Weight | Invariant |
---|---|
1,0 |
.
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["8 4"];
|
In[4]:=
|
Alexander[K][t]
|
KnotTheory::loading: Loading precomputed data in PD4Knots`.
|
Out[4]=
|
In[5]:=
|
Conway[K][z]
|
Out[5]=
|
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]=
|
In[7]:=
|
{KnotDet[K], KnotSignature[K]}
|
Out[7]=
|
{ 19, -2 } |
In[8]:=
|
Jones[K][q]
|
KnotTheory::loading: Loading precomputed data in Jones4Knots`.
|
Out[8]=
|
In[9]:=
|
HOMFLYPT[K][a, z]
|
KnotTheory::credits: The HOMFLYPT program was written by Scott Morrison.
|
Out[9]=
|
In[10]:=
|
Kauffman[K][a, z]
|
KnotTheory::loading: Loading precomputed data in Kauffman4Knots`.
|
Out[10]=
|
Vassiliev invariants
V2 and V3: | (-3, 1) |
V2,1 through V6,9: |
|
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.
Khovanov Homology
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 8 4. Nonzero entries off the critical diagonals (if any exist) are highlighted in red.
|
-4 | -3 | -2 | -1 | 0 | 1 | 2 | 3 | 4 | χ | |||||||||
7 | 1 | 1 | |||||||||||||||||
5 | 0 | ||||||||||||||||||
3 | 2 | 1 | 1 | ||||||||||||||||
1 | 1 | -1 | |||||||||||||||||
-1 | 2 | 2 | 0 | ||||||||||||||||
-3 | 2 | 2 | 0 | ||||||||||||||||
-5 | 1 | 1 | 0 | ||||||||||||||||
-7 | 1 | 2 | 1 | ||||||||||||||||
-9 | 1 | -1 | |||||||||||||||||
-11 | 1 | 1 |
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 17, 2005, 14:44:34)... | |
In[2]:= | Crossings[Knot[8, 4]] |
Out[2]= | 8 |
In[3]:= | PD[Knot[8, 4]] |
Out[3]= | PD[X[6, 2, 7, 1], X[14, 10, 15, 9], X[10, 3, 11, 4], X[2, 13, 3, 14], X[12, 5, 13, 6], X[16, 8, 1, 7], X[4, 11, 5, 12], X[8, 16, 9, 15]] |
In[4]:= | GaussCode[Knot[8, 4]] |
Out[4]= | GaussCode[1, -4, 3, -7, 5, -1, 6, -8, 2, -3, 7, -5, 4, -2, 8, -6] |
In[5]:= | BR[Knot[8, 4]] |
Out[5]= | BR[4, {-1, -1, -1, 2, -1, 2, 3, -2, 3}] |
In[6]:= | alex = Alexander[Knot[8, 4]][t] |
Out[6]= | 2 5 2 |
In[7]:= | Conway[Knot[8, 4]][z] |
Out[7]= | 2 4 1 - 3 z - 2 z |
In[8]:= | Select[AllKnots[], (alex === Alexander[#][t])&] |
Out[8]= | {Knot[8, 4]} |
In[9]:= | {KnotDet[Knot[8, 4]], KnotSignature[Knot[8, 4]]} |
Out[9]= | {19, -2} |
In[10]:= | J=Jones[Knot[8, 4]][q] |
Out[10]= | -5 2 3 3 3 2 3 |
In[11]:= | Select[AllKnots[], (J === Jones[#][q] || (J /. q-> 1/q) === Jones[#][q])&] |
Out[11]= | {Knot[8, 4]} |
In[12]:= | A2Invariant[Knot[8, 4]][q] |
Out[12]= | -16 -10 -6 -4 -2 2 4 6 8 10 -1 + q + q + q - q - q - q + q + q + q + q |
In[13]:= | Kauffman[Knot[8, 4]][a, z] |
Out[13]= | 22 4 z 3 2 7 z 2 2 4 2 |
In[14]:= | {Vassiliev[2][Knot[8, 4]], Vassiliev[3][Knot[8, 4]]} |
Out[14]= | {0, 1} |
In[15]:= | Kh[Knot[8, 4]][q, t] |
Out[15]= | 2 2 1 1 1 2 1 1 2 2 t |