applications.collages.collageAlgebra:
{
  line = { polyline((-1,1),(1,-1)) },
  
  i1 = scale(1),
  i2 = rotate(180),
  I = < i1, i2 >,
  
  f1 = similarity((-1,1) -> (-1,1), (1,-1) -> (-1,-1)),
  f2 = similarity((-1,1) -> (-1,-1), (1,-1) -> (1,-1)),
  F = <f1, f2>,
  
  g1 = similarity((-1,1) -> (-1,1), (1,-1) -> (0,0)),
  g2 = similarity((-1,1) -> (1,-1), (1,-1) -> (0,0)),
  G = <g1,g2>,
  
  r1 = similarity((-1,1) -> (-1,1), (1,-1) -> (-1,-1)),
  r2 = use(r1) . translate(2,0),
  refine = <r1, r2>,
  
  invert = translate(-2,0) . similarity((-1,1) -> (-1,1), (-1,-1) -> (1,-1)),
  invert = <invert>
  
}
