9 20

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9 19.gif

9_19

9 21.gif

9_21

9 20.gif Visit 9 20's page at the Knot Server (KnotPlot driven, includes 3D interactive images!)

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9 20 Quick Notes



From knotilus

Knot presentations

Planar diagram presentation X1425 X3,10,4,11 X5,14,6,15 X7,16,8,17 X11,1,12,18 X15,6,16,7 X17,13,18,12 X13,8,14,9 X9,2,10,3
Gauss code -1, 9, -2, 1, -3, 6, -4, 8, -9, 2, -5, 7, -8, 3, -6, 4, -7, 5
Dowker-Thistlethwaite code 4 10 14 16 2 18 8 6 12
Conway Notation [31212]

Three dimensional invariants

Symmetry type Reversible
Unknotting number 2
3-genus 3
Bridge index 2
Super bridge index [math]\displaystyle{ \{4,6\} }[/math]
Nakanishi index 1
Maximal Thurston-Bennequin number [-12][1]
Hyperbolic Volume 9.6443
A-Polynomial See Data:9 20/A-polynomial

[edit Notes for 9 20's three dimensional invariants]

Four dimensional invariants

Smooth 4 genus [math]\displaystyle{ 2 }[/math]
Topological 4 genus [math]\displaystyle{ 2 }[/math]
Concordance genus [math]\displaystyle{ 3 }[/math]
Rasmussen s-Invariant -4

[edit Notes for 9 20's four dimensional invariants]

Polynomial invariants

Alexander polynomial [math]\displaystyle{ -t^3+5 t^2-9 t+11-9 t^{-1} +5 t^{-2} - t^{-3} }[/math]
Conway polynomial [math]\displaystyle{ -z^6-z^4+2 z^2+1 }[/math]
2nd Alexander ideal (db, data sources) [math]\displaystyle{ \{1\} }[/math]
Determinant and Signature { 41, -4 }
Jones polynomial [math]\displaystyle{ 1-2 q^{-1} +4 q^{-2} -5 q^{-3} +7 q^{-4} -7 q^{-5} +6 q^{-6} -5 q^{-7} +3 q^{-8} - q^{-9} }[/math]
HOMFLY-PT polynomial (db, data sources) [math]\displaystyle{ -z^2 a^8-a^8+2 z^4 a^6+5 z^2 a^6+2 a^6-z^6 a^4-4 z^4 a^4-5 z^2 a^4-2 a^4+z^4 a^2+3 z^2 a^2+2 a^2 }[/math]
Kauffman polynomial (db, data sources) [math]\displaystyle{ z^3 a^{11}+3 z^4 a^{10}-z^2 a^{10}+5 z^5 a^9-5 z^3 a^9+2 z a^9+5 z^6 a^8-6 z^4 a^8+3 z^2 a^8-a^8+3 z^7 a^7-7 z^3 a^7+2 z a^7+z^8 a^6+5 z^6 a^6-16 z^4 a^6+10 z^2 a^6-2 a^6+5 z^7 a^5-12 z^5 a^5+5 z^3 a^5+z^8 a^4+z^6 a^4-11 z^4 a^4+11 z^2 a^4-2 a^4+2 z^7 a^3-7 z^5 a^3+6 z^3 a^3+z^6 a^2-4 z^4 a^2+5 z^2 a^2-2 a^2 }[/math]
The A2 invariant [math]\displaystyle{ -q^{28}+q^{24}-q^{22}+q^{20}-q^{18}+q^{14}-q^{12}+2 q^{10}-q^8+q^6+q^4+1 }[/math]
The G2 invariant [math]\displaystyle{ q^{148}-2 q^{146}+3 q^{144}-4 q^{142}+2 q^{140}-q^{138}-2 q^{136}+9 q^{134}-12 q^{132}+15 q^{130}-13 q^{128}+5 q^{126}+2 q^{124}-13 q^{122}+23 q^{120}-27 q^{118}+23 q^{116}-13 q^{114}-q^{112}+15 q^{110}-23 q^{108}+25 q^{106}-21 q^{104}+5 q^{102}+7 q^{100}-17 q^{98}+16 q^{96}-5 q^{94}-9 q^{92}+23 q^{90}-24 q^{88}+14 q^{86}+3 q^{84}-26 q^{82}+44 q^{80}-44 q^{78}+30 q^{76}-4 q^{74}-21 q^{72}+43 q^{70}-45 q^{68}+33 q^{66}-17 q^{64}-6 q^{62}+22 q^{60}-28 q^{58}+22 q^{56}-6 q^{54}-9 q^{52}+19 q^{50}-19 q^{48}+7 q^{46}+8 q^{44}-23 q^{42}+31 q^{40}-28 q^{38}+12 q^{36}+10 q^{34}-26 q^{32}+36 q^{30}-30 q^{28}+17 q^{26}-q^{24}-13 q^{22}+21 q^{20}-19 q^{18}+14 q^{16}-3 q^{14}-2 q^{12}+5 q^{10}-5 q^8+4 q^6-q^4+q^2 }[/math]

Vassiliev invariants

V2 and V3: (2, -4)
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
[math]\displaystyle{ 8 }[/math] [math]\displaystyle{ -32 }[/math] [math]\displaystyle{ 32 }[/math] [math]\displaystyle{ \frac{412}{3} }[/math] [math]\displaystyle{ \frac{68}{3} }[/math] [math]\displaystyle{ -256 }[/math] [math]\displaystyle{ -\frac{1856}{3} }[/math] [math]\displaystyle{ -\frac{224}{3} }[/math] [math]\displaystyle{ -128 }[/math] [math]\displaystyle{ \frac{256}{3} }[/math] [math]\displaystyle{ 512 }[/math] [math]\displaystyle{ \frac{3296}{3} }[/math] [math]\displaystyle{ \frac{544}{3} }[/math] [math]\displaystyle{ \frac{42751}{15} }[/math] [math]\displaystyle{ -\frac{4124}{15} }[/math] [math]\displaystyle{ \frac{64924}{45} }[/math] [math]\displaystyle{ \frac{833}{9} }[/math] [math]\displaystyle{ \frac{2911}{15} }[/math]

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 [math]\displaystyle{ t^rq^j }[/math] are shown, along with their alternating sums [math]\displaystyle{ \chi }[/math] (fixed [math]\displaystyle{ j }[/math], alternation over [math]\displaystyle{ r }[/math]). The squares with yellow highlighting are those on the "critical diagonals", where [math]\displaystyle{ j-2r=s+1 }[/math] or [math]\displaystyle{ j-2r=s-1 }[/math], where [math]\displaystyle{ s= }[/math]-4 is the signature of 9 20. Nonzero entries off the critical diagonals (if any exist) are highlighted in red.   
\ r
  \  
j \
-7-6-5-4-3-2-1012χ
1         11
-1        1 -1
-3       31 2
-5      32  -1
-7     42   2
-9    33    0
-11   34     -1
-13  23      1
-15 13       -2
-17 2        2
-191         -1
Integral Khovanov Homology

(db, data source)

  
[math]\displaystyle{ \dim{\mathcal G}_{2r+i}\operatorname{KH}^r_{\mathbb Z} }[/math] [math]\displaystyle{ i=-5 }[/math] [math]\displaystyle{ i=-3 }[/math]
[math]\displaystyle{ r=-7 }[/math] [math]\displaystyle{ {\mathbb Z} }[/math]
[math]\displaystyle{ r=-6 }[/math] [math]\displaystyle{ {\mathbb Z}^{2}\oplus{\mathbb Z}_2 }[/math] [math]\displaystyle{ {\mathbb Z} }[/math]
[math]\displaystyle{ r=-5 }[/math] [math]\displaystyle{ {\mathbb Z}^{3}\oplus{\mathbb Z}_2^{2} }[/math] [math]\displaystyle{ {\mathbb Z}^{2} }[/math]
[math]\displaystyle{ r=-4 }[/math] [math]\displaystyle{ {\mathbb Z}^{3}\oplus{\mathbb Z}_2^{3} }[/math] [math]\displaystyle{ {\mathbb Z}^{3} }[/math]
[math]\displaystyle{ r=-3 }[/math] [math]\displaystyle{ {\mathbb Z}^{4}\oplus{\mathbb Z}_2^{3} }[/math] [math]\displaystyle{ {\mathbb Z}^{3} }[/math]
[math]\displaystyle{ r=-2 }[/math] [math]\displaystyle{ {\mathbb Z}^{3}\oplus{\mathbb Z}_2^{4} }[/math] [math]\displaystyle{ {\mathbb Z}^{4} }[/math]
[math]\displaystyle{ r=-1 }[/math] [math]\displaystyle{ {\mathbb Z}^{2}\oplus{\mathbb Z}_2^{3} }[/math] [math]\displaystyle{ {\mathbb Z}^{3} }[/math]
[math]\displaystyle{ r=0 }[/math] [math]\displaystyle{ {\mathbb Z}^{2}\oplus{\mathbb Z}_2^{2} }[/math] [math]\displaystyle{ {\mathbb Z}^{3} }[/math]
[math]\displaystyle{ r=1 }[/math] [math]\displaystyle{ {\mathbb Z}\oplus{\mathbb Z}_2 }[/math] [math]\displaystyle{ {\mathbb Z} }[/math]
[math]\displaystyle{ r=2 }[/math] [math]\displaystyle{ {\mathbb Z}_2 }[/math] [math]\displaystyle{ {\mathbb Z} }[/math]

Computer Talk

Much of the above data can be recomputed by Mathematica using the package KnotTheory`. See A Sample KnotTheory` Session.

[math]\displaystyle{ \textrm{Include}(\textrm{ColouredJonesM.mhtml}) }[/math]

In[1]:=    
<< KnotTheory`
Loading KnotTheory` (version of August 17, 2005, 14:44:34)...
In[2]:=
Crossings[Knot[9, 20]]
Out[2]=  
9
In[3]:=
PD[Knot[9, 20]]
Out[3]=  
PD[X[1, 4, 2, 5], X[3, 10, 4, 11], X[5, 14, 6, 15], X[7, 16, 8, 17], 
 X[11, 1, 12, 18], X[15, 6, 16, 7], X[17, 13, 18, 12], 

X[13, 8, 14, 9], X[9, 2, 10, 3]]
In[4]:=
GaussCode[Knot[9, 20]]
Out[4]=  
GaussCode[-1, 9, -2, 1, -3, 6, -4, 8, -9, 2, -5, 7, -8, 3, -6, 4, -7, 5]
In[5]:=
BR[Knot[9, 20]]
Out[5]=  
BR[4, {-1, -1, -1, 2, -1, -3, 2, -3, -3}]
In[6]:=
alex = Alexander[Knot[9, 20]][t]
Out[6]=  
      -3   5    9            2    3

11 - t + -- - - - 9 t + 5 t - t

           2   t
t
In[7]:=
Conway[Knot[9, 20]][z]
Out[7]=  
       2    4    6
1 + 2 z  - z  - z
In[8]:=
Select[AllKnots[], (alex === Alexander[#][t])&]
Out[8]=  
{Knot[9, 20], Knot[10, 149], Knot[11, NonAlternating, 26]}
In[9]:=
{KnotDet[Knot[9, 20]], KnotSignature[Knot[9, 20]]}
Out[9]=  
{41, -4}
In[10]:=
J=Jones[Knot[9, 20]][q]
Out[10]=  
     -9   3    5    6    7    7    5    4    2

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

          8    7    6    5    4    3    2   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, 20], Knot[11, NonAlternating, 90]}
In[12]:=
A2Invariant[Knot[9, 20]][q]
Out[12]=  
     -28    -24    -22    -20    -18    -14    -12    2     -8    -6

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

                                                     10
                                                    q

  -4
q
In[13]:=
Kauffman[Knot[9, 20]][a, z]
Out[13]=  
    2      4      6    8      7        9        2  2       4  2

-2 a - 2 a - 2 a - a + 2 a z + 2 a z + 5 a z + 11 a z +

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

  11  3      2  4       4  4       6  4      8  4      10  4
 a   z  - 4 a  z  - 11 a  z  - 16 a  z  - 6 a  z  + 3 a   z  - 

    3  5       5  5      9  5    2  6    4  6      6  6      8  6
 7 a  z  - 12 a  z  + 5 a  z  + a  z  + a  z  + 5 a  z  + 5 a  z  + 

    3  7      5  7      7  7    4  8    6  8
2 a z + 5 a z + 3 a z + a z + a z
In[14]:=
{Vassiliev[2][Knot[9, 20]], Vassiliev[3][Knot[9, 20]]}
Out[14]=  
{0, -4}
In[15]:=
Kh[Knot[9, 20]][q, t]
Out[15]=  
2    3      1        2        1        3        2        3

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

5    3    19  7    17  6    15  6    15  5    13  5    13  4

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

   3        4        3       3       4      2      3     t    t      2
 ------ + ------ + ----- + ----- + ----- + ---- + ---- + -- + - + q t
  11  4    11  3    9  3    9  2    7  2    7      5      3   q
q t q t q t q t q t q t q t q