theorem Th114:
  for i being Nat, f being FinSequence st
    1<=i & i<=len f holds (Rev f).i=f.(len f -i+1)
proof
  let i be Nat,f be FinSequence;
  assume that
A1: 1<=i and
A2: i<=len f;
  i in dom (f) by A1,A2,FINSEQ_3:25;
  hence thesis by FINSEQ_5:58;
end;
