src/FOL/ex/List.thy

proper symbol markup with \isamath, \isatext;
support sub/super scripts:

(*  Title:      FOL/ex/list
    ID:         $Id$
    Author:     Tobias Nipkow
    Copyright   1991  University of Cambridge

Examples of simplification and induction on lists
*)

List = Nat2 +

types 'a list
arities list :: (term)term

consts
   hd           :: 'a list => 'a  
   tl           :: 'a list => 'a list
   forall       :: ['a list, 'a => o] => o  
   len          :: 'a list => nat  
   at           :: ['a list, nat] => 'a  
   Nil          :: ('a list)                         ("[]")
   Cons         :: ['a, 'a list] => 'a list          (infixr "." 80)
   "++"         :: ['a list, 'a list] => 'a list     (infixr 70)

rules
 list_ind "[| P([]);  ALL x l. P(l)-->P(x . l) |] ==> All(P)"

 forall_cong 
  "[| l = l';  !!x. P(x)<->P'(x) |] ==> forall(l,P) <-> forall(l',P')"

 list_distinct1 "~[] = x . l"
 list_distinct2 "~x . l = []"

 list_free      "x . l = x' . l' <-> x=x' & l=l'"

 app_nil        "[]++l = l"
 app_cons       "(x . l)++l' = x .(l++l')"
 tl_eq  "tl(m . q) = q"
 hd_eq  "hd(m . q) = m"

 forall_nil "forall([],P)"
 forall_cons "forall(x . l,P) <-> P(x) & forall(l,P)"

 len_nil "len([]) = 0"
 len_cons "len(m . q) = succ(len(q))"

 at_0 "at(m . q,0) = m"
 at_succ "at(m . q,succ(n)) = at(q,n)"

end