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4 (* ||A|| A project by Andrea Asperti *)
6 (* ||I|| Developers: *)
7 (* ||T|| The HELM team. *)
8 (* ||A|| http://helm.cs.unibo.it *)
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15 include "basic_2/grammar/tsts.ma".
17 (* SAME TOP TERM STRUCTURE **************************************************)
19 (* Main properties **********************************************************)
21 (* Basic_1: was: iso_trans *)
22 theorem tsts_trans: Transitive … tsts.
24 #I #V1 #V #T1 #T #X #H
25 elim (tsts_inv_pair1 … H) -H #V2 #T2 #H destruct //
28 theorem tsts_canc_sn: ∀T,T1. T ≂ T1 → ∀T2. T ≂ T2 → T1 ≂ T2.
29 /3 width=3 by tsts_trans, tsts_sym/ qed-.
31 theorem tsts_canc_dx: ∀T1,T. T1 ≂ T → ∀T2. T2 ≂ T → T1 ≂ T2.
32 /3 width=3 by tsts_trans, tsts_sym/ qed-.