8 4

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8 3.gif

8_3

8 5.gif

8_5

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8 4 Quick Notes



Somewhat symmetric representation

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

Symmetry type Reversible
Unknotting number 2
3-genus 2
Bridge index 2
Super bridge index
Nakanishi index 1
Maximal Thurston-Bennequin number [-7][-3]
Hyperbolic Volume 5.50049
A-Polynomial See Data:8 4/A-polynomial

[edit Notes for 8 4's three dimensional invariants]

Four dimensional invariants

Smooth 4 genus
Topological 4 genus
Concordance genus
Rasmussen s-Invariant 2

[edit Notes for 8 4's four dimensional invariants]

Polynomial invariants

Alexander polynomial
Conway polynomial
2nd Alexander ideal (db, data sources)
Determinant and Signature { 19, -2 }
Jones polynomial
HOMFLY-PT polynomial (db, data sources)
Kauffman polynomial (db, data sources)
The A2 invariant
The G2 invariant

Vassiliev invariants

V2 and V3: (-3, 1)
V2,1 through V6,9:
V2,1 V3,1 V4,1 V4,2 V4,3 V5,1 V5,2 V5,3 V5,4 V6,1 V6,2 V6,3 V6,4 V6,5 V6,6 V6,7 V6,8 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.

\ r
  \  
j \
-4-3-2-101234χ
7        11
5         0
3      21 1
1     1   -1
-1    22   0
-3   22    0
-5  11     0
-7 12      1
-9 1       -1
-111        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

-5 - -- + - + 5 t - 2 t

     2   t
t
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

-3 + q - -- + -- - -- + - + 2 q - q + q

           4    3    2   q
q q q
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]=  
                                             2
    2     4   z            3         2   7 z     2  2      4  2

-2 - -- + a - - + a z + 2 a z + 10 z + ---- - a z - 3 a z +

     2        a                            2
    a                                     a

            3                                           4
  6  2   4 z         3      3  3      5  3       4   5 z       2  4
 a  z  + ---- - 3 a z  - 5 a  z  + 2 a  z  - 11 z  - ---- - 3 a  z  + 
          a                                            2
                                                      a

              5                            6              7
    4  4   4 z       5      3  5      6   z       2  6   z       7
 3 a  z  - ---- - a z  + 3 a  z  + 3 z  + -- + 2 a  z  + -- + a z
            a                              2             a
a
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

-- + - + ------ + ----- + ----- + ----- + ----- + ---- + ---- + --- +

3   q    11  4    9  3    7  3    7  2    5  2    5      3      q

q q t q t q t q t q t q t q t

          3  2    3  3    7  4
q t + 2 q t + q t + q t