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4 (* ||A|| A project by Andrea Asperti *)
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15 include "ground/lib/bool.ma".
17 (* DISJUNCTION FOR BOOLEANS *************************************************)
19 (* Advanced constructions ***************************************************)
21 lemma commutative_orb:
25 lemma orb_true_dx (b):
29 lemma orb_true_sn (b):
33 (* Advanced inversions ******************************************************)
35 lemma orb_inv_false_dx (b1) (b2):
36 (b1 ∨ b2) = Ⓕ → ∧∧ b1 = Ⓕ & b2 = Ⓕ.
37 * normalize /2 width=1 by conj/ #b2 #H destruct