Definition redacc :
  list (poly A0 eqA ltM) -> list (poly A0 eqA ltM) -> list (poly A0 eqA ltM).

Theorem redacc_cb : forall (L1 L2 : list (poly A0 eqA ltM)) (p : poly A0 eqA ltM), In p (redacc L1 L2) -> Cb A A0 eqA plusA multA eqA_dec n ltM ltM_dec p (L1 ++ L2).