diff -r 81ae96996223 -r 1be466c58a26 src/HOL/Tools/ATP/atp_proof_redirect.ML
--- a/src/HOL/Tools/ATP/atp_proof_redirect.ML	Mon May 14 15:54:26 2012 +0200
+++ b/src/HOL/Tools/ATP/atp_proof_redirect.ML	Mon May 14 15:54:26 2012 +0200
@@ -97,7 +97,7 @@
   string_of_context gamma ^ " \<turnstile> " ^ Atom.string_of c
 
 val string_of_ref_graph =
-  sequents_of_ref_graph #> map string_of_sequent #> implode
+  sequents_of_ref_graph #> map string_of_sequent #> cat_lines
 
 fun redirect_sequent tainted bot (gamma, c) =
   if member atom_eq tainted c then