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_Psucc : forall x,
gen_phiPOS1 (Pos.succ x) == 1 + (gen_phiPOS1 x).