7 4

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7 3.gif

7_3

7 5.gif

7_5

7 4.gif Visit 7 4's page at the Knot Server (KnotPlot driven, includes 3D interactive images!)

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Visit 7 4's page at the original Knot Atlas!

Simplest version of Endless knot symbol.



Celtic or pseudo-Celtic knot
Mongolian ornament
Susan Williams' medallion [1], the "Endless knot" of Buddhism [2]
Ornamental "Endless knot"
a knot seen at the Castle of Kornik [3]
A 7-4 knot reduced from TakaraMusubi with 9 crossings [4]
TakaraMusubi knot seen in Japanese symbols, or Kolam in South India [5]
Buddhist Endless Knot
Ornamental Endless Knot
Albrecht Dürer knot, 16th-century
A laser cut by Tom Longtin [6]
Unicursal hexagram of occultism
Logo of the raelian sect
Lissajous curve : x=cos 3t , y=sin 2t, z=sin 7t
French europa stamp 2023


Knot presentations

Planar diagram presentation X6271 X12,6,13,5 X14,8,1,7 X8,14,9,13 X2,12,3,11 X10,4,11,3 X4,10,5,9
Gauss code 1, -5, 6, -7, 2, -1, 3, -4, 7, -6, 5, -2, 4, -3
Dowker-Thistlethwaite code 6 10 12 14 4 2 8
Conway Notation [313]

Three dimensional invariants

Symmetry type Reversible
Unknotting number 2
3-genus 1
Bridge index 2
Super bridge index
Nakanishi index 1
Maximal Thurston-Bennequin number Failed to parse (syntax error): {\displaystyle \text{$\$$Failed}}
Hyperbolic Volume 5.13794
A-Polynomial See Data:7 4/A-polynomial

[edit Notes for 7 4's three dimensional invariants]

Four dimensional invariants

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

[edit Notes for 7 4's four dimensional invariants]

Polynomial invariants

Alexander polynomial
Conway polynomial
2nd Alexander ideal (db, data sources)
Determinant and Signature { 15, 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: (4, 8)
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 7 4. Nonzero entries off the critical diagonals (if any exist) are highlighted in red.

\ r
  \  
j \
01234567χ
17       1-1
15        0
13     21 -1
11    1   1
9   12   1
7  21    1
5  1     1
312      -1
11       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[7, 4]]
Out[2]=  
7
In[3]:=
PD[Knot[7, 4]]
Out[3]=  
PD[X[6, 2, 7, 1], X[12, 6, 13, 5], X[14, 8, 1, 7], X[8, 14, 9, 13], 
  X[2, 12, 3, 11], X[10, 4, 11, 3], X[4, 10, 5, 9]]
In[4]:=
GaussCode[Knot[7, 4]]
Out[4]=  
GaussCode[1, -5, 6, -7, 2, -1, 3, -4, 7, -6, 5, -2, 4, -3]
In[5]:=
BR[Knot[7, 4]]
Out[5]=  
BR[4, {1, 1, 2, -1, 2, 2, 3, -2, 3}]
In[6]:=
alex = Alexander[Knot[7, 4]][t]
Out[6]=  
     4

-7 + - + 4 t

t
In[7]:=
Conway[Knot[7, 4]][z]
Out[7]=  
       2
1 + 4 z
In[8]:=
Select[AllKnots[], (alex === Alexander[#][t])&]
Out[8]=  
{Knot[7, 4], Knot[9, 2]}
In[9]:=
{KnotDet[Knot[7, 4]], KnotSignature[Knot[7, 4]]}
Out[9]=  
{15, 2}
In[10]:=
J=Jones[Knot[7, 4]][q]
Out[10]=  
       2      3      4      5      6    7    8
q - 2 q  + 3 q  - 2 q  + 3 q  - 2 q  + q  - q
In[11]:=
Select[AllKnots[], (J === Jones[#][q] || (J /. q-> 1/q) === Jones[#][q])&]
Out[11]=  
{Knot[7, 4]}
In[12]:=
A2Invariant[Knot[7, 4]][q]
Out[12]=  
 2    4    8    10      12    14    16    20    24    26
q  - q  + q  + q   + 2 q   + q   + q   - q   - q   - q
In[13]:=
Kauffman[Knot[7, 4]][a, z]
Out[13]=  
                           2      2      2    2      3      3      3
 -8   2    4 z   4 z   2 z    3 z    4 z    z    4 z    8 z    2 z

-a + -- + --- + --- + ---- - ---- - ---- + -- - ---- - ---- - ---- +

       4    9     7      8      6      4     2     9      7      5
      a    a     a      a      a      a     a     a      a      a

    3      4      4    5      5      5    6    6
 2 z    3 z    3 z    z    3 z    2 z    z    z
 ---- - ---- + ---- + -- + ---- + ---- + -- + --
   3      8      4     9     7      5     8    6
a a a a a a a a
In[14]:=
{Vassiliev[2][Knot[7, 4]], Vassiliev[3][Knot[7, 4]]}
Out[14]=  
{0, 8}
In[15]:=
Kh[Knot[7, 4]][q, t]
Out[15]=  
     3      3      5  2      7  2    7  3    9  3      9  4    11  4

q + q + 2 q t + q t + 2 q t + q t + q t + 2 q t + q t +

    13  5    13  6    17  7
2 q t + q t + q t