matita/matita/contribs/lambdadelta/static_2/syntax/sh.ma

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   3 (*      ||M||                                                             *)
   4 (*      ||A||       A project by Andrea Asperti                           *)
   5 (*      ||T||                                                             *)
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  10 (*       \ /        This file is distributed under the terms of the       *)
  11 (*        v         GNU General Public License Version 2                  *)
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  13 (**************************************************************************)
  14
  15 include "ground/lib/arith.ma".
  16 include "static_2/notation/functions/upspoon_2.ma".
  17
  18 (* SORT HIERARCHY ***********************************************************)
  19
  20 (* sort hierarchy specification *)
  21 record sh: Type[0] ≝ {
  22   next: nat → nat (* next sort in the hierarchy *)
  23 }.
  24
  25 interpretation "next sort (sort hierarchy)"
  26    'UpSpoon h s = (next h s).
  27
  28 definition sh_is_next (h): relation nat ≝
  29            λs1,s2. ⫯[h]s1 = s2.