reserve a, b, r, s for Real;
reserve n, m for Nat,
  F for Subset-Family of Closed-Interval-TSpace (r,s);
reserve C for IntervalCover of F;
reserve G for IntervalCoverPts of C;

theorem Th60:
  F is Cover of Closed-Interval-TSpace(r,s) & F is open connected
  & r <= s implies 2 <= len G
proof
  assume
A1: F is Cover of Closed-Interval-TSpace(r,s) & F is open & F is
  connected & r <= s;
  then 1 <= len C by Th51;
  then 1+1 <= len C + 1 by XREAL_1:6;
  hence thesis by A1,Def3;
end;
