8 2

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8 1.gif

8_1

8 3.gif

8_3

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8 2 Quick Notes


8 2 Further Notes and Views

Knot presentations

Planar diagram presentation X1425 X5,12,6,13 X3,11,4,10 X11,3,12,2 X7,14,8,15 X9,16,10,1 X13,6,14,7 X15,8,16,9
Gauss code -1, 4, -3, 1, -2, 7, -5, 8, -6, 3, -4, 2, -7, 5, -8, 6
Dowker-Thistlethwaite code 4 10 12 14 16 2 6 8
Conway Notation [512]

Three dimensional invariants

Symmetry type Reversible
Unknotting number 2
3-genus 3
Bridge index 2
Super bridge index
Nakanishi index 1
Maximal Thurston-Bennequin number [-11][1]
Hyperbolic Volume 4.93524
A-Polynomial See Data:8 2/A-polynomial

[edit Notes for 8 2's three dimensional invariants]

Four dimensional invariants

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

[edit Notes for 8 2's four dimensional invariants]

Polynomial invariants

Alexander polynomial
Conway polynomial
2nd Alexander ideal (db, data sources)
Determinant and Signature { 17, -4 }
Jones polynomial
HOMFLY-PT polynomial (db, data sources)
Kauffman polynomial (db, data sources)
The A2 invariant
The G2 invariant

Vassiliev invariants

V2 and V3: (0, 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 -4 is the signature of 8 2. Nonzero entries off the critical diagonals (if any exist) are highlighted in red.   
\ r
  \  
j \
-6-5-4-3-2-1012χ
1        11
-1         0
-3      21 1
-5     11  0
-7    21   1
-9   11    0
-11  12     -1
-13 11      0
-15 1       -1
-171        1
Integral Khovanov Homology

(db, data source)

  

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, 2]]
Out[2]=  
8
In[3]:=
PD[Knot[8, 2]]
Out[3]=  
PD[X[1, 4, 2, 5], X[5, 12, 6, 13], X[3, 11, 4, 10], X[11, 3, 12, 2], 
  X[7, 14, 8, 15], X[9, 16, 10, 1], X[13, 6, 14, 7], X[15, 8, 16, 9]]
In[4]:=
GaussCode[Knot[8, 2]]
Out[4]=  
GaussCode[-1, 4, -3, 1, -2, 7, -5, 8, -6, 3, -4, 2, -7, 5, -8, 6]
In[5]:=
BR[Knot[8, 2]]
Out[5]=  
BR[3, {-1, -1, -1, -1, -1, 2, -1, 2}]
In[6]:=
alex = Alexander[Knot[8, 2]][t]
Out[6]=  
     -3   3    3            2    3

3 - t + -- - - - 3 t + 3 t - t

          2   t
t
In[7]:=
Conway[Knot[8, 2]][z]
Out[7]=  
       4    6
1 - 3 z  - z
In[8]:=
Select[AllKnots[], (alex === Alexander[#][t])&]
Out[8]=  
{Knot[8, 2], Knot[11, NonAlternating, 6]}
In[9]:=
{KnotDet[Knot[8, 2]], KnotSignature[Knot[8, 2]]}
Out[9]=  
{17, -4}
In[10]:=
J=Jones[Knot[8, 2]][q]
Out[10]=  
     -8   2    2    3    3    2    2    1

1 + q - -- + -- - -- + -- - -- + -- - -

          7    6    5    4    3    2   q
q q q q q q
In[11]:=
Select[AllKnots[], (J === Jones[#][q] || (J /. q-> 1/q) === Jones[#][q])&]
Out[11]=  
{Knot[8, 2]}
In[12]:=
A2Invariant[Knot[8, 2]][q]
Out[12]=  
     -24    -18    -16    -12    -10    -6    -4    -2
1 + q    - q    - q    - q    + q    + q   + q   + q
In[13]:=
Kauffman[Knot[8, 2]][a, z]
Out[13]=  
    2      4    6    3      5      7      9        2  2       4  2

-3 a - 3 a - a + a z + a z - a z - a z + 7 a z + 12 a z +

    6  2    8  2    10  2      3  3    5  3      7  3      9  3
 3 a  z  - a  z  + a   z  + 3 a  z  - a  z  - 2 a  z  + 2 a  z  - 

    2  4       4  4      6  4      8  4      3  5      5  5
 5 a  z  - 12 a  z  - 5 a  z  + 2 a  z  - 4 a  z  - 2 a  z  + 

    7  5    2  6      4  6      6  6    3  7    5  7
2 a z + a z + 3 a z + 2 a z + a z + a z
In[14]:=
{Vassiliev[2][Knot[8, 2]], Vassiliev[3][Knot[8, 2]]}
Out[14]=  
{0, 1}
In[15]:=
Kh[Knot[8, 2]][q, t]
Out[15]=  
 -5   2      1        1        1        1        1        2

q + -- + ------ + ------ + ------ + ------ + ------ + ------ +

      3    17  6    15  5    13  5    13  4    11  4    11  3
     q    q   t    q   t    q   t    q   t    q   t    q   t

   1       1       2      1      1     t       2
 ----- + ----- + ----- + ---- + ---- + -- + q t
  9  3    9  2    7  2    7      5      3
q t q t q t q t q t q