reserve U for Universe;
reserve x for Element of U;

theorem Th19:
  for X being set for n being non zero Nat st
  Funcs(Seg n,{X}) is Element of U holds X is Element of U
  proof
    let X be set;
    let n be non zero Nat;
    assume
A1: Funcs(Seg n,{X}) is Element of U;
    set R = Seg n --> X;
    reconsider f = Seg n --> X as Function of Seg n, {X};
    f in Funcs(Seg n, {X}) by FUNCT_2:8;
    then f is Element of U by A1,CLASSES4:def 1;
    then {X} is Element of U by CLASSES4:40;
    hence thesis by Th18;
  end;
