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

theorem Th49:
  3RP.0 = 0 & 3RP.1 = 1
proof
  0 is Point of I[01] by BORSUK_1:43;
  hence 3RP.0 = 1/2 * 0 by Def7
    .= 0;
  1 is Point of I[01] by BORSUK_1:43;
  hence 3RP.1 = 2 * 1 - 1 by Def7
    .= 1;
end;
