matita/matita/contribs/lambdadelta/ground/lib/stream_tls_plus.ma

   1 (**************************************************************************)
   2 (*       ___                                                              *)
   3 (*      ||M||                                                             *)
   4 (*      ||A||       A project by Andrea Asperti                           *)
   5 (*      ||T||                                                             *)
   6 (*      ||I||       Developers:                                           *)
   7 (*      ||T||         The HELM team.                                      *)
   8 (*      ||A||         http://helm.cs.unibo.it                             *)
   9 (*      \   /                                                             *)
  10 (*       \ /        This file is distributed under the terms of the       *)
  11 (*        v         GNU General Public License Version 2                  *)
  12 (*                                                                        *)
  13 (**************************************************************************)
  14
  15 include "ground/arith/nat_plus.ma".
  16 include "ground/lib/stream_tls.ma".
  17
  18 (* ITERATED TAIL FOR STREAMS ************************************************)
  19
  20 (* Constructions with nplus *************************************************)
  21
  22 lemma stream_tls_plus (A) (n1) (n2) (t):
  23       ⇂*[n1]⇂*[n2]t = ⇂*{A}[n1+n2]t.
  24 #A #n1 #n2 #t
  25 <nplus_comm @(niter_plus … t)
  26 qed.