diff --git a/sta/b52/2026/fall/README.md b/sta/b52/2026/fall/README.md
index e69de29..8547ed1 100644
--- a/sta/b52/2026/fall/README.md
+++ b/sta/b52/2026/fall/README.md
@@ -0,0 +1,4 @@
+
+$$
+E[E[X|Y]] = E[X]
+$$
\ No newline at end of file