 reserve a,Z1,Z2,Z3 for set,
         x,y,z for object,
         k for Nat;
 reserve S for RelStr;
 reserve P,Q for non empty flat Poset;
 reserve p,p1,p2 for Element of P;
 reserve K for non empty Chain of P;
 reserve X,Y for non empty set;

theorem ThFlatten04:
  for x, y being Element of FlatPoset(X) holds
    x <= y iff x = X or x = y by LemFlatten01,LemFlatten02;
