reserve T for non empty TopSpace,
  a, b, c, d for Point of T;

theorem Th66:
  [1/2,0] in ICC & [1,1] in ICC
proof
A1: 0 <= 2 * (1/2) - 1;
  1/2 is Point of I[01] & 0 is Point of I[01] by BORSUK_1:43;
  hence [1/2,0] in ICC by A1,Def10;
  1 is Point of I[01] & 1 <= 2 * 1 - 1 by BORSUK_1:43;
  hence thesis by Def10;
end;
