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LINKED POLYGRAM
Polygram: from the Greek poly "several" and gramma "letter, writing". 
A linked polygram
is a knot or link
obtained by the interlacing of a polygram,
and deciding, each time two sides cross, which side passes above the other.
There are two remarkable ways to interlace a polygram with Schläfli
symbol {p/q}, with p > 2q:
 either by making each side pass
alternatively above and below the sides that are secant (and it can be
proved that this is always possible); we get the socalled "alternate"
polygram, equivalent to the cylindrical
billiard knot or link of type (p,q).
 or by making each side passing above
all the others until its middle, and then below. The resulting knot or
link is then equivalent to the toric
knot or link T(p,q).
The toric and alternate polygrams are not equivalent
when .
If we accept any kind of above and below passages, we obtain all the possible knots and links. Indeed, all knots or links have a projection that is a polygram.
Here are the first examples of toric polygrams, along with the corresponding toric knots:
pentagram {5/2},

hexagram {6/2}, Solomon's seal or star of David prime link 6_{1}^{2} 
heptagram {7/2}

heptagram {7/3} prime knot 12 n 242 
octogram {8/2} prime link 8_{1}^{2} 
octogram {8/3} 
enneagram {9/2} prime knot 9_{1} 
enneagram {9/3} 
enneagram {9/4} 
decagram {10/2} prime link 10_{1}^{2} 
decagram{10/3} 
decagram {10/4} 
undecagram {11/2} 
undecagram {11/3} 
undecagram {11/4} 
undecagram {11/5} 
dodecagram {12/2} 
dodecagram {12/3} 
dodecagram {12/4} 
dodecagram {12/5} 
Views showing the trick (due to Alain Esculier) used to trace the polygrams; the strips form in fact a section of hyperboloid. 
Here are some examples of "alternate" polygrams (see also the Turk's heads, and the Brunnian links):
Some images of interlaced pentagrams:
Moroccan flag 
Ethiopian flag 


Some images of interlaced hexagrams:
Israeli flag 

A superb hexagram composed of two Penrose triangles. 
Composed of two mobius bands 
alternate heptagram {7/2} 
alternate octogram {8/3} 
alternate nonagram {9/3} 
alternate decagram {10/2} medallion of an Iranian Koran, 14^{th} century 
dodecagram {12/4}: neither alternate nor toric!
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© Robert FERRÉOL 2018