8 17

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8 16.gif

8_16

8 18.gif

8_18

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8 17 Quick Notes



A knot in Brian Sanderson's Garden [1]

Knot presentations

Planar diagram presentation X6271 X14,8,15,7 X8394 X2,13,3,14 X12,5,13,6 X4,9,5,10 X16,12,1,11 X10,16,11,15
Gauss code 1, -4, 3, -6, 5, -1, 2, -3, 6, -8, 7, -5, 4, -2, 8, -7
Dowker-Thistlethwaite code 6 8 12 14 4 16 2 10
Conway Notation [.2.2]

Three dimensional invariants

Symmetry type Negative amphicheiral
Unknotting number 1
3-genus 3
Bridge index 3
Super bridge index 4
Nakanishi index 1
Maximal Thurston-Bennequin number [-5][-5]
Hyperbolic Volume 10.9859
A-Polynomial See Data:8 17/A-polynomial

[edit Notes for 8 17's three dimensional invariants] 8_17 is the first negatively amphicheiral knot in the Rolfsen Table. Namely, it is equal to the inverse of its mirror, yet it is different from both its inverse and its mirror.

Four dimensional invariants

Smooth 4 genus
Topological 4 genus
Concordance genus
Rasmussen s-Invariant 0

[edit Notes for 8 17's four dimensional invariants]

Polynomial invariants

Alexander polynomial
Conway polynomial
2nd Alexander ideal (db, data sources)
Determinant and Signature { 37, 0 }
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, 0)
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 0 is the signature of 8 17. Nonzero entries off the critical diagonals (if any exist) are highlighted in red.   
\ r
  \  
j \
-4-3-2-101234χ
9        11
7       2 -2
5      31 2
3     32  -1
1    43   1
-1   34    1
-3  23     -1
-5 13      2
-7 2       -2
-91        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, 17]]
Out[2]=  
8
In[3]:=
PD[Knot[8, 17]]
Out[3]=  
PD[X[6, 2, 7, 1], X[14, 8, 15, 7], X[8, 3, 9, 4], X[2, 13, 3, 14], 
  X[12, 5, 13, 6], X[4, 9, 5, 10], X[16, 12, 1, 11], X[10, 16, 11, 15]]
In[4]:=
GaussCode[Knot[8, 17]]
Out[4]=  
GaussCode[1, -4, 3, -6, 5, -1, 2, -3, 6, -8, 7, -5, 4, -2, 8, -7]
In[5]:=
BR[Knot[8, 17]]
Out[5]=  
BR[3, {-1, -1, 2, -1, 2, -1, 2, 2}]
In[6]:=
alex = Alexander[Knot[8, 17]][t]
Out[6]=  
      -3   4    8            2    3

11 - t + -- - - - 8 t + 4 t - t

           2   t
t
In[7]:=
Conway[Knot[8, 17]][z]
Out[7]=  
     2      4    6
1 - z  - 2 z  - z
In[8]:=
Select[AllKnots[], (alex === Alexander[#][t])&]
Out[8]=  
{Knot[8, 17], Knot[11, NonAlternating, 53]}
In[9]:=
{KnotDet[Knot[8, 17]], KnotSignature[Knot[8, 17]]}
Out[9]=  
{37, 0}
In[10]:=
J=Jones[Knot[8, 17]][q]
Out[10]=  
     -4   3    5    6            2      3    4

7 + q - -- + -- - - - 6 q + 5 q - 3 q + q

          3    2   q
q q
In[11]:=
Select[AllKnots[], (J === Jones[#][q] || (J /. q-> 1/q) === Jones[#][q])&]
Out[11]=  
{Knot[8, 17]}
In[12]:=
A2Invariant[Knot[8, 17]][q]
Out[12]=  
      -12    -10    -8    -4   2       2    4    8    10    12

-1 + q - q + q - q + -- + 2 q - q + q - q + q

                               2
q
In[13]:=
Kauffman[Knot[8, 17]][a, z]
Out[13]=  
                                                  2      2
     -2    2   z    2 z            3        2   z    3 z       2  2

-1 - a - a + -- + --- + 2 a z + a z + 8 z - -- + ---- + 3 a z -

                3    a                           4     2
               a                                a     a

            3      3                               4      4
  4  2   4 z    6 z         3      3  3       4   z    6 z
 a  z  - ---- - ---- - 6 a z  - 4 a  z  - 14 z  + -- - ---- - 
           3     a                                 4     2
          a                                       a     a

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

              7
    2  6   2 z         7
 4 a  z  + ---- + 2 a z
a
In[14]:=
{Vassiliev[2][Knot[8, 17]], Vassiliev[3][Knot[8, 17]]}
Out[14]=  
{0, 0}
In[15]:=
Kh[Knot[8, 17]][q, t]
Out[15]=  
4           1       2       1       3       2      3      3

- + 4 q + ----- + ----- + ----- + ----- + ----- + ---- + --- + 3 q t + q 9 4 7 3 5 3 5 2 3 2 3 q t

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

    3        3  2      5  2    5  3      7  3    9  4
3 q t + 2 q t + 3 q t + q t + 2 q t + q t