
theorem Th73:
  for A be Interval holds A in Borel_Sets
proof
    let A be Interval;
A1: A in Family_of_Intervals by MEASUR10:def 1;
A2: Family_of_Intervals c= Field_generated_by Family_of_Intervals
      by SRINGS_3:21;
    Field_generated_by Family_of_Intervals
     c= sigma Field_generated_by Family_of_Intervals by PROB_1:def 9;
    hence thesis by A2,A1,MEASUR10:6;
end;
