applications.collages.collageAlgebra("filled dragons"):
{
  ter = { filledPolygon((-1,0),(0,-1/sqrt(3)),(1,0),(0,1/sqrt(3))) },
  sq = { filledPolygon((-1,0),(0,-1),(1,0),(0,1)) },
  yad = {
    filledPolygon((0,-1/sqrt(3)),
                  (cos(30)/sqrt(3),-1/(2*sqrt(3))),
                  (cos(30)/sqrt(3),1/(2*sqrt(3))),
                  (0,1/sqrt(3)),
                  (-cos(30)/sqrt(3),1/(2*sqrt(3))),
                  (-cos(30)/sqrt(3),-1/(2*sqrt(3)))) },
  
  % the terdragon:
  t1 = similarity((-1,0) -> (-1,0), (1,0) -> (0,1/sqrt(3))),
  t2 = similarity((-1,0) -> (0,1/sqrt(3)), (1,0) -> (0,-1/sqrt(3))),
  t3 = similarity((-1,0) -> (0,-1/sqrt(3)), (1,0) -> (1,0)),
  T = < t1, t2, t3 >,
  
  % the Harter-Heightway dragon and the twindragon:
  f1 = similarity((-1,0) -> (-1,0), (1,0) -> (0,-1)),
  f2 = similarity((-1,0) -> (1,0), (1,0) -> (0,-1)),
  F = <f1, f2>,
  
  i1 = rotate(-45),
  i2 = rotate(135),
  I = < i1, i2 >,
  
  % ... and "yet another dragon":
  g1 = translate(0,1/sqrt(3)) . scale(1/sqrt(3)) . rotate(30),
  g2 = translate(0,1/sqrt(3)) . scale(1/sqrt(3)) . rotate(-90),
  g3 = translate(0,1/sqrt(3)) . scale(1/sqrt(3)) . rotate(-210),
  G = <g1,g2,g3>
  
}
