Definition spolyf :
  forall (p q : list (Term A n)) (Cp : canonical A0 eqA ltM p)
    (Cq : canonical A0 eqA ltM q), list (Term A n).

Theorem spolyf_canonical : forall (p q : list (Term A n)) (Cp : canonical A0 eqA ltM p) (Cq : canonical A0 eqA ltM q), canonical A0 eqA ltM (spolyf p q Cp Cq).