diff -r acc8ebf980ca -r b8c7eb0c2f89 src/Pure/Thy/thy_output.ML
--- a/src/Pure/Thy/thy_output.ML	Thu Mar 15 17:45:54 2012 +0100
+++ b/src/Pure/Thy/thy_output.ML	Thu Mar 15 19:02:34 2012 +0100
@@ -626,8 +626,6 @@
 
 (* embedded lemma *)
 
-val _ = Keyword.keyword "by";
-
 val _ =
   Context.>> (Context.map_theory
    (antiquotation (Binding.name "lemma")