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14
15 include "static_2/syntax/term.ma".
16
17 (* BINDERS FOR LOCAL ENVIRONMENTS ******************************************)
18
19 inductive bind: Type[0] ≝
20 | BUnit: bind1 → bind
21 | BPair: bind2 → term → bind
22 .
23
24 (* Basic properties ********************************************************)
25
26 lemma eq_bind_dec: ∀I1,I2:bind. Decidable (I1 = I2).
27 * #I1 [2: #V1 ] * #I2 [2,4: #V2 ]
28 [1: elim (eq_bind2_dec I1 I2) #HI
29     [ elim (eq_term_dec V1 V2) #HV ]
30 |4: elim (eq_bind1_dec I1 I2) #HI
31 ]
32 /2 width=1 by or_introl/
33 @or_intror #H destruct /2 width=1 by/
34 qed-.