--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/BNF/Ctr_Sugar.thy Tue Oct 01 14:05:25 2013 +0200
@@ -0,0 +1,29 @@
+(* Title: HOL/BNF/Ctr_Sugar.thy
+ Author: Jasmin Blanchette, TU Muenchen
+ Copyright 2012
+
+Wrapping existing freely generated type's constructors.
+*)
+
+header {* Wrapping Existing Freely Generated Type's Constructors *}
+
+theory Ctr_Sugar
+imports BNF_Util
+keywords
+ "wrap_free_constructors" :: thy_goal and
+ "no_discs_sels" and
+ "rep_compat"
+begin
+
+lemma iffI_np: "\<lbrakk>x \<Longrightarrow> \<not> y; \<not> x \<Longrightarrow> y\<rbrakk> \<Longrightarrow> \<not> x \<longleftrightarrow> y"
+by (erule iffI) (erule contrapos_pn)
+
+lemma iff_contradict:
+"\<not> P \<Longrightarrow> P \<longleftrightarrow> Q \<Longrightarrow> Q \<Longrightarrow> R"
+"\<not> Q \<Longrightarrow> P \<longleftrightarrow> Q \<Longrightarrow> P \<Longrightarrow> R"
+by blast+
+
+ML_file "Tools/bnf_ctr_sugar_tactics.ML"
+ML_file "Tools/bnf_ctr_sugar.ML"
+
+end