Section fractran_mma.
Variables (ll : list (nat*nat)) (Hll : Forall (fun c => fst c <> 0 /\ snd c <> 0) ll).
Let i := 1.
Definition fractran_mma := mma_fractran_step i ll i.

Lemma fractran_mma_sound v x w :
v#>dst = 0
-> fractran_compute ll (v#>src) x
-> fractran_stop ll x
-> w = v[x/src]
-> (i,fractran_mma) /MM2/ (i,v) ->> (length fractran_mma+i,w).