reserve v,x for object;
reserve D,V,A for set;
reserve n for Nat;
reserve p,q for PartialPredicate of D;
reserve f,g for BinominativeFunction of D;
reserve D for non empty set;
reserve d for Element of D;
reserve f,g for BinominativeFunction of D;
reserve p,q,r,s for PartialPredicate of D;

theorem
  <*p,id dom p,p*> is SFHT of D
  proof
    set f = id dom p;
    for d holds d in dom p & p.d = TRUE & d in dom f & f.d in dom p implies
    p.(f.d) = TRUE by FUNCT_1:17;
    then <*p,f,p*> in SFHTs(D);
    hence thesis;
  end;
