diff --git a/src/todo.txt b/src/todo.txt
index d034ee5..ce92841 100644
--- a/src/todo.txt
+++ b/src/todo.txt
@@ -1,3 +1,7 @@
+- Intruder should at least have one copy of each type that an agent can
+  construct, I think in any case. Proof needed for single identifier need.
+  Furthermore reduction if type flaw testing; only one constant needed.
+- Functions should have a signature.
 - State counter is off by one. Should start at 1, or should add 1 at printing.
 - Make filter switch, allowing maybe for some claims only to be evaluated.
   --check=Secret, --check-all as default.