added equals_cong;
authorwenzelm
Sat, 28 Jan 2006 17:28:54 +0100
changeset 18820 24dcd5b0e26b
parent 18819 67f9347ea21d
child 18821 213b7341abb6
added equals_cong;
src/Pure/drule.ML
--- a/src/Pure/drule.ML	Sat Jan 28 17:28:53 2006 +0100
+++ b/src/Pure/drule.ML	Sat Jan 28 17:28:54 2006 +0100
@@ -65,6 +65,7 @@
   val transitive_thm: thm
   val symmetric_fun: thm -> thm
   val extensional: thm -> thm
+  val equals_cong: thm
   val imp_cong: thm
   val swap_prems_eq: thm
   val equal_abs_elim: cterm  -> thm -> thm
@@ -627,6 +628,9 @@
     abstract_rule "x" (snd (Thm.dest_comb (fst (dest_equals (cprop_of eq))))) eq
   in equal_elim (eta_conversion (cprop_of eq')) eq' end;
 
+val equals_cong =
+  store_standard_thm_open "equals_cong" (Thm.reflexive (read_prop "x == y"));
+
 val imp_cong =
   let
     val ABC = read_prop "PROP A ==> PROP B == PROP C"