theorem Th10:
  for n being Nat holds len Gauge(T,n) >= 4
proof
  let n be Nat;
  set G = Gauge(T,n);
A1: len G = 2|^n + 3 by Def1;
  2|^n >= n + 1 by NEWTON:85;
  then
A2: len G >= n + 1 + 3 by A1,XREAL_1:6;
  n+4 >= 4 by NAT_1:12;
  hence thesis by A2,XXREAL_0:2;
end;
