reserve X for non empty CUNITSTR;
reserve a, b for Complex;
reserve x, y for Point of X;
reserve X for ComplexUnitarySpace;
reserve x, y, z, u, v for Point of X;

theorem Th22:
  x.|.(y-z) = x.|.y - x.|.z
proof
  x .|. (y - z) = x .|. y + x .|. (-z) by Th12
    .= x .|. y + ( - x .|. z ) by Th19;
  hence thesis;
end;
