reserve x,y for set,
  n,m for Nat,
  r,s for Real;

theorem
  for F be Function, X be finite set
  ex f be FinSequence st F|X, f are_fiberwise_equipotent
proof
  let F be Function, X be finite set;
A1: card(dom(F|X)) = card(dom(F|X));
  for n holds P[n] from NAT_1:sch 2(Lm1,Lm2);
  hence thesis by A1;
end;
