
theorem Th16:
  for a, b being Point of I[01] holds ]. a, b .[ is Subset of I[01]
proof
  let a, b be Point of I[01];
A1: [. a,b .] is Subset of I[01] by BORSUK_1:40,XXREAL_2:def 12;
  ]. a,b .[ c= [. a,b .] by XXREAL_1:25;
  hence thesis by A1,XBOOLE_1:1;
end;
