src/CCL/hered.thy
author clasohm
Thu Sep 16 12:20:38 1993 +0200 (1993-09-16)
changeset 0 a5a9c433f639
permissions -rw-r--r--
Initial revision
     1 (*  Title: 	CCL/hered.thy
     2     ID:         $Id$
     3     Author: 	Martin Coen
     4     Copyright   1993  University of Cambridge
     5 
     6 Hereditary Termination - cf. Martin Lo\"f
     7 
     8 Note that this is based on an untyped equality and so lam x.b(x) is only 
     9 hereditarily terminating if ALL x.b(x) is.  Not so useful for functions!
    10 
    11 *)
    12 
    13 Hered = Type +
    14 
    15 consts
    16       (*** Predicates ***)
    17   HTTgen     ::       "i set => i set"
    18   HTT        ::       "i set"
    19 
    20 
    21 rules
    22 
    23   (*** Definitions of Hereditary Termination ***)
    24 
    25   HTTgen_def 
    26   "HTTgen(R) == {t. t=true | t=false | (EX a b.t=<a,b>      & a : R & b : R) | \
    27 \                                      (EX f.  t=lam x.f(x) & (ALL x.f(x) : R))}"
    28   HTT_def       "HTT == gfp(HTTgen)"
    29 
    30 end