--- a/src/HOL/ex/Iff_Oracle.thy Mon Jun 08 21:38:41 2020 +0200
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,78 +0,0 @@
-(* Title: HOL/ex/Iff_Oracle.thy
- Author: Lawrence C Paulson, Cambridge University Computer Laboratory
- Author: Makarius
-*)
-
-section \<open>Example of Declaring an Oracle\<close>
-
-theory Iff_Oracle
-imports Main
-begin
-
-subsection \<open>Oracle declaration\<close>
-
-text \<open>
- This oracle makes tautologies of the form \<^prop>\<open>P \<longleftrightarrow> P \<longleftrightarrow> P \<longleftrightarrow> P\<close>.
- The length is specified by an integer, which is checked to be even
- and positive.
-\<close>
-
-oracle iff_oracle = \<open>
- let
- fun mk_iff 1 = Var (("P", 0), \<^typ>\<open>bool\<close>)
- | mk_iff n = HOLogic.mk_eq (Var (("P", 0), \<^typ>\<open>bool\<close>), mk_iff (n - 1));
- in
- fn (thy, n) =>
- if n > 0 andalso n mod 2 = 0
- then Thm.global_cterm_of thy (HOLogic.mk_Trueprop (mk_iff n))
- else raise Fail ("iff_oracle: " ^ string_of_int n)
- end
-\<close>
-
-
-subsection \<open>Oracle as low-level rule\<close>
-
-ML \<open>iff_oracle (\<^theory>, 2)\<close>
-ML \<open>iff_oracle (\<^theory>, 10)\<close>
-
-ML \<open>
- \<^assert> (map (#1 o #1) (Thm_Deps.all_oracles [iff_oracle (\<^theory>, 10)]) = [\<^oracle_name>\<open>iff_oracle\<close>]);
-\<close>
-
-text \<open>These oracle calls had better fail.\<close>
-
-ML \<open>
- (iff_oracle (\<^theory>, 5); error "Bad oracle")
- handle Fail _ => writeln "Oracle failed, as expected"
-\<close>
-
-ML \<open>
- (iff_oracle (\<^theory>, 1); error "Bad oracle")
- handle Fail _ => writeln "Oracle failed, as expected"
-\<close>
-
-
-subsection \<open>Oracle as proof method\<close>
-
-method_setup iff =
- \<open>Scan.lift Parse.nat >> (fn n => fn ctxt =>
- SIMPLE_METHOD
- (HEADGOAL (resolve_tac ctxt [iff_oracle (Proof_Context.theory_of ctxt, n)])
- handle Fail _ => no_tac))\<close>
-
-
-lemma "A \<longleftrightarrow> A"
- by (iff 2)
-
-lemma "A \<longleftrightarrow> A \<longleftrightarrow> A \<longleftrightarrow> A \<longleftrightarrow> A \<longleftrightarrow> A \<longleftrightarrow> A \<longleftrightarrow> A \<longleftrightarrow> A \<longleftrightarrow> A"
- by (iff 10)
-
-lemma "A \<longleftrightarrow> A \<longleftrightarrow> A \<longleftrightarrow> A \<longleftrightarrow> A"
- apply (iff 5)?
- oops
-
-lemma A
- apply (iff 1)?
- oops
-
-end