diff --git a/numbers.md b/numbers.md
index 5aa2a36c0..efb01447c 100644
--- a/numbers.md
+++ b/numbers.md
@@ -3,3 +3,4 @@
 - #1 [[self]], [[non dualistic]]
 - #2 [[fork]], [[dualistic]]
 - #3 [[merge]], a [[triangle]]
+- #4 [[2 2]], two [[forks]]