theorem Th22:
  len(N)<=0 implies the LTLnew of N = {}v
proof
  assume
A1: len(N)<=0;
  len(the LTLnew of N) -1 < [\ len(the LTLnew of N) /] by INT_1:def 6;
  then len(the LTLnew of N) -1 +1 <0+1 by A1,XREAL_1:8;
  hence thesis by Th16;
end;
