8 16

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8 15.gif

8_15

8 17.gif

8_17

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8 16 Quick Notes



Square depiction.

Knot presentations

Planar diagram presentation X6271 X14,6,15,5 X16,11,1,12 X12,7,13,8 X8394 X4,9,5,10 X10,15,11,16 X2,14,3,13
Gauss code 1, -8, 5, -6, 2, -1, 4, -5, 6, -7, 3, -4, 8, -2, 7, -3
Dowker-Thistlethwaite code 6 8 14 12 4 16 2 10
Conway Notation [.2.20]

Three dimensional invariants

Symmetry type Reversible
Unknotting number 2
3-genus 3
Bridge index 3
Super bridge index 4
Nakanishi index 1
Maximal Thurston-Bennequin number [-8][-2]
Hyperbolic Volume 10.579
A-Polynomial See Data:8 16/A-polynomial

[edit Notes for 8 16's three dimensional invariants]

Four dimensional invariants

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

[edit Notes for 8 16's four dimensional invariants]

Polynomial invariants

Alexander polynomial
Conway polynomial
2nd Alexander ideal (db, data sources)
Determinant and Signature { 35, -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: (1, -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 16. Nonzero entries off the critical diagonals (if any exist) are highlighted in red.   
\ r
  \  
j \
-5-4-3-2-10123χ
5        1-1
3       2 2
1      21 -1
-1     42  2
-3    33   0
-5   33    0
-7  23     1
-9 13      -2
-11 2       2
-131        -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, 16]]
Out[2]=  
8
In[3]:=
PD[Knot[8, 16]]
Out[3]=  
PD[X[6, 2, 7, 1], X[14, 6, 15, 5], X[16, 11, 1, 12], X[12, 7, 13, 8], 
  X[8, 3, 9, 4], X[4, 9, 5, 10], X[10, 15, 11, 16], X[2, 14, 3, 13]]
In[4]:=
GaussCode[Knot[8, 16]]
Out[4]=  
GaussCode[1, -8, 5, -6, 2, -1, 4, -5, 6, -7, 3, -4, 8, -2, 7, -3]
In[5]:=
BR[Knot[8, 16]]
Out[5]=  
BR[3, {-1, -1, 2, -1, -1, 2, -1, 2}]
In[6]:=
alex = Alexander[Knot[8, 16]][t]
Out[6]=  
      -3   4    8            2    3

-9 + t - -- + - + 8 t - 4 t + t

           2   t
t
In[7]:=
Conway[Knot[8, 16]][z]
Out[7]=  
     2      4    6
1 + z  + 2 z  + z
In[8]:=
Select[AllKnots[], (alex === Alexander[#][t])&]
Out[8]=  
{Knot[8, 16], Knot[10, 156], Knot[11, NonAlternating, 15], 
  Knot[11, NonAlternating, 56], Knot[11, NonAlternating, 58]}
In[9]:=
{KnotDet[Knot[8, 16]], KnotSignature[Knot[8, 16]]}
Out[9]=  
{35, -2}
In[10]:=
J=Jones[Knot[8, 16]][q]
Out[10]=  
      -6   3    5    6    6    6          2

-4 - q + -- - -- + -- - -- + - + 3 q - q

           5    4    3    2   q
q q q q
In[11]:=
Select[AllKnots[], (J === Jones[#][q] || (J /. q-> 1/q) === Jones[#][q])&]
Out[11]=  
{Knot[8, 16], Knot[10, 156]}
In[12]:=
A2Invariant[Knot[8, 16]][q]
Out[12]=  
     -18    -16    -14    -10    -8   2     -4   2     4    6

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

                                      6          2
q q
In[13]:=
Kauffman[Knot[8, 16]][a, z]
Out[13]=  
    2    4   z              3        5        2       2  2      4  2

-2 a - a + - + 3 a z + 4 a z + 2 a z + 5 z + 10 a z + 4 a z -

            a

            3
  6  2   2 z         3       3  3      5  3    7  3      4
 a  z  - ---- - 6 a z  - 10 a  z  - 5 a  z  + a  z  - 8 z  - 
          a

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

    2  6      4  6        7      3  7
8 a z + 5 a z + 2 a z + 2 a z
In[14]:=
{Vassiliev[2][Knot[8, 16]], Vassiliev[3][Knot[8, 16]]}
Out[14]=  
{0, -1}
In[15]:=
Kh[Knot[8, 16]][q, t]
Out[15]=  
3    4     1        2        1       3       2       3       3

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

3   q    13  5    11  4    9  4    9  3    7  3    7  2    5  2

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

  3      3     2 t              2      3  2    5  3
 ---- + ---- + --- + 2 q t + q t  + 2 q  t  + q  t
  5      3      q
q t q t