Arguments InA {A}{eqA} x _.
Arguments AMap.In {elt} x m.

Lemma unlift_m_inv :
forall tp i (Htid : i < (num_threads tp).+1) ord
(Hunlift: unlift (ordinal_pos_incr (num_threads tp))
(Ordinal (n:=(num_threads tp).+1)
(m:=i) Htid)=Some ord),
nat_of_ord ord = i.