(* Basic properties *********************************************************)
-(* Basic_1: was: term_dec *)
lemma eq_term_dec: ∀T1,T2:term. Decidable (T1 = T2).
#T1 elim T1 -T1 #I1 [| #V1 #T1 #IHV1 #IHT1 ] * #I2 [2,4: #V2 #T2 ]
[1,4: @or_intror #H destruct
]
qed-.
-(* Basic_1: was: thead_x_y_y *)
lemma discr_tpair_xy_y: ∀I,V,T. ②{I} V. T = T → ⊥.
#I #V #T elim T -T
[ #J #H destruct
elim (eq_term_dec T1 T2) /3 width=1 by or_introl/ #HT12 destruct
@or_intror @conj // #HT12 destruct /2 width=1 by/
qed-.
-
-(* Basic_1: removed theorems 3:
- not_void_abst not_abbr_void not_abst_void
-*)