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4 (* ||A|| A project by Andrea Asperti *)
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7 (* ||T|| The HELM team. *)
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15 include "ground/arith/ynat_le.ma".
16 include "ground/arith/ynat_lt_pred.ma".
18 (* STRICT ORDER FOR NON-NEGATIVE INTEGERS WITH INFINITY *********************)
20 (* Destructions with yle and ypred ******************************************)
22 (*** ylt_fwd_le_pred2 *)
23 lemma ylt_des_le_pred_dx (x) (y): x < y → x ≤ ↓y.
26 elim (nlt_inv_gen … H) -H #Hm #_
27 /2 width=1 by yle_inj/