(* Properties with context-free sort-irrelevant equivalence *****************)
lemma cpr_abbr_pos_tneqx (h) (G) (L) (V) (T1):
- ∃∃T2. ❪G,L❫ ⊢ +ⓓV.T1 ➡[h] T2 & (+ⓓV.T1 ≛ T2 → ⊥).
+ ∃∃T2. ❪G,L❫ ⊢ +ⓓV.T1 ➡[h,0] T2 & (+ⓓV.T1 ≛ T2 → ⊥).
#h #G #L #V #U1
elim (cpr_subst h G (L.ⓓV) U1 … 0) [|*: /2 width=4 by drops_refl/ ] #U2 #T2 #HU12 #HTU2
elim (teqx_dec U1 U2) [ -HU12 #HU12 | -HTU2 #HnU12 ]