applications.collages.collageAlgebra:
{
  a-part = { filledPolygon((0,0),(1,0),(1,1),(0,1)) },
  b-part = { polyline((0,0),(1,1)) , polyline((1,0),(0,1))  },
  
  id = scale(1),
  
  c1 = translate(0,1),
  c2 = translate(1,1),
  c3 = scale(-1,1) . rotate(-90) . translate(1,0),
  corner = <id, c1, c2, c3>,
  
  e = translate(0,1),
  edge = <id, e>,
  
  q1 = rotate(0),
  q2 = rotate(90),
  q3 = rotate(180),
  q4 = rotate(270),
  quarters = <q1, q2, q3, q4>,
  
  outline = { polygon((0,0),(1,0),(1,1),(0,1)) },
  
  S = {polygon((-.5,-.5),(.5,-.5),(.5,.5),(-.5,.5))},
  C = { filledPolygon((0,0),(1,0),(1,1),(0,1))[.8],
        polygon((0,0),(1,0),(1,1),(0,1)),
        polyline((.975,0),(.975,.975),(0,.975)) width .05},
  E = { filledPolygon((0,0),(1,0),(1,1),(0,1))[.8],
        polygon((0,0),(1,0),(1,1),(0,1)),
        polyline((1,.975),(0,.975)) width .05}
  
}
