diff --git a/test/open-problems.txt b/test/open-problems.txt
new file mode 100644
index 0000000..b13ebad
--- /dev/null
+++ b/test/open-problems.txt
@@ -0,0 +1,3 @@
+- What is the protocol claim with the least states, where the states
+  differ between warshall-old and the new warshall? Investigate the
+  proof there.