9 18

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9 17.gif

9_17

9 19.gif

9_19

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9 18 Quick Notes


9 18 Further Notes and Views

Knot presentations

Planar diagram presentation X1425 X3,12,4,13 X5,14,6,15 X9,18,10,1 X17,6,18,7 X7,16,8,17 X15,8,16,9 X13,10,14,11 X11,2,12,3
Gauss code -1, 9, -2, 1, -3, 5, -6, 7, -4, 8, -9, 2, -8, 3, -7, 6, -5, 4
Dowker-Thistlethwaite code 4 12 14 16 18 2 10 8 6
Conway Notation [3222]

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 [-14][3]
Hyperbolic Volume 10.0577
A-Polynomial See Data:9 18/A-polynomial

[edit Notes for 9 18's three dimensional invariants]

Four dimensional invariants

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

[edit Notes for 9 18's four dimensional invariants]

Polynomial invariants

Alexander polynomial
Conway polynomial
2nd Alexander ideal (db, data sources)
Determinant and Signature { 41, -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: (6, -15)
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 9 18. Nonzero entries off the critical diagonals (if any exist) are highlighted in red.

\ r
  \  
j \
-9-8-7-6-5-4-3-2-10χ
-3         11
-5        21-1
-7       3  3
-9      32  -1
-11     43   1
-13    33    0
-15   34     -1
-17  13      2
-19 13       -2
-21 1        1
-231         -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[9, 18]]
Out[2]=  
9
In[3]:=
PD[Knot[9, 18]]
Out[3]=  
PD[X[1, 4, 2, 5], X[3, 12, 4, 13], X[5, 14, 6, 15], X[9, 18, 10, 1], 
 X[17, 6, 18, 7], X[7, 16, 8, 17], X[15, 8, 16, 9], X[13, 10, 14, 11], 

X[11, 2, 12, 3]]
In[4]:=
GaussCode[Knot[9, 18]]
Out[4]=  
GaussCode[-1, 9, -2, 1, -3, 5, -6, 7, -4, 8, -9, 2, -8, 3, -7, 6, -5, 4]
In[5]:=
BR[Knot[9, 18]]
Out[5]=  
BR[4, {-1, -1, -1, -2, 1, -2, -2, -2, -3, 2, -3}]
In[6]:=
alex = Alexander[Knot[9, 18]][t]
Out[6]=  
     4    10             2

13 + -- - -- - 10 t + 4 t

     2   t
t
In[7]:=
Conway[Knot[9, 18]][z]
Out[7]=  
       2      4
1 + 6 z  + 4 z
In[8]:=
Select[AllKnots[], (alex === Alexander[#][t])&]
Out[8]=  
{Knot[9, 18], Knot[11, Alternating, 246]}
In[9]:=
{KnotDet[Knot[9, 18]], KnotSignature[Knot[9, 18]]}
Out[9]=  
{41, -4}
In[10]:=
J=Jones[Knot[9, 18]][q]
Out[10]=  
  -11    2    4    6    7    7    6    5    2     -2

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

        10    9    8    7    6    5    4    3
q q q q q q q q
In[11]:=
Select[AllKnots[], (J === Jones[#][q] || (J /. q-> 1/q) === Jones[#][q])&]
Out[11]=  
{Knot[9, 18]}
In[12]:=
A2Invariant[Knot[9, 18]][q]
Out[12]=  
  -34    2     -26    -20    -18    2     -12    2     -8    -6

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

        28                         16           10
q q q
In[13]:=
Kauffman[Knot[9, 18]][a, z]
Out[13]=  
 4    6    10      7        13        4  2      6  2      10  2

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

    12  2      5  3      7  3    9  3      13  3    4  4      6  4
 3 a   z  - 2 a  z  - 4 a  z  + a  z  - 3 a   z  + a  z  - 4 a  z  - 

    8  4      10  4      12  4      5  5    7  5      9  5
 2 a  z  - 2 a   z  - 5 a   z  + 2 a  z  + a  z  - 5 a  z  - 

    11  5    13  5      6  6      8  6    10  6      12  6      7  7
 3 a   z  + a   z  + 3 a  z  + 2 a  z  + a   z  + 2 a   z  + 2 a  z  + 

    9  7      11  7    8  8    10  8
4 a z + 2 a z + a z + a z
In[14]:=
{Vassiliev[2][Knot[9, 18]], Vassiliev[3][Knot[9, 18]]}
Out[14]=  
{0, -15}
In[15]:=
Kh[Knot[9, 18]][q, t]
Out[15]=  
 -5    -3     1        1        1        3        1        3

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

            23  9    21  8    19  8    19  7    17  7    17  6
           q   t    q   t    q   t    q   t    q   t    q   t

   3        4        3        3        4        3        3       2
 ------ + ------ + ------ + ------ + ------ + ------ + ----- + ----- + 
  15  6    15  5    13  5    13  4    11  4    11  3    9  3    9  2
 q   t    q   t    q   t    q   t    q   t    q   t    q  t    q  t

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