
theorem
  for F being set, A being FinSequence of bool F, i being Element of NAT
  holds A is Reduction of A,i
proof
  let F be set, A be FinSequence of bool F, i be Element of NAT;
  ( for j being Element of NAT st j in dom A & j <> i holds A.j = A.j)& A.
  i c= A .i;
  hence thesis by Def5;
end;
