diff -r 02d75712061d -r 3ef83c265aca src/Pure/Proof/proof_syntax.ML
--- a/src/Pure/Proof/proof_syntax.ML	Fri Oct 19 22:01:25 2001 +0200
+++ b/src/Pure/Proof/proof_syntax.ML	Fri Oct 19 22:02:02 2001 +0200
@@ -70,6 +70,8 @@
       [("_Lam", [paramsT, proofT] ---> proofT, Mixfix ("(1\\<Lambda>_./ _)", [0, 3], 3)),
        ("Appt", [proofT, aT] ---> proofT, Mixfix ("(1_ \\<cdot>/ _)", [4, 5], 4)),
        ("AppP", [proofT, proofT] ---> proofT, Mixfix ("(1_ \\<bullet>/ _)", [4, 5], 4))])
+  |> Sign.add_modesyntax_i (("latex", false),
+      [("_Lam", [paramsT, proofT] ---> proofT, Mixfix ("(1\\<^bold>\\<lambda>_./ _)", [0, 3], 3))])
   |> Sign.add_trrules_i (map Syntax.ParsePrintRule
       [(Syntax.mk_appl (Constant "_Lam")
           [Syntax.mk_appl (Constant "_Lam0") [Variable "l", Variable "m"], Variable "A"],