diff --git a/main/math.tex b/main/math.tex
index fab0602..a7af3a2 100644
--- a/main/math.tex
+++ b/main/math.tex
@@ -13,6 +13,7 @@
 \newcommand{\C}{\mathbb{C}}
 \newcommand{\Q}{\mathbb{Q}}
 \newcommand{\Z}{\mathbb{Z}}
+\newcommand{\I}{\mathbb{I}}
 \newcommand{\E}{\mathbb{E}}
 \newcommand{\8}{\infty}
 \newcommand{\dx}{\mbox{d}}