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,f,q*> is SFHT of D &
  <*q,g,r*> is SFHT of D & <*PP_inversion(q),g,r*> is SFHT of D
  implies <*p,PP_composition(f,g),r*> is SFHT of D
  proof
    PP_or(r,r) = r;
    hence thesis by Th24;
  end;
