Section ALMOST_RING.
Variable ARth : almost_ring_theory 0 1 radd rmul rsub ropp req.
Add Morphism rsub with signature (req ==> req ==> req) as rsub_ext3.

Lemma ARgen_phiPOS_mult :
forall x y, gen_phiPOS1 (x * y) == gen_phiPOS1 x * gen_phiPOS1 y.