src/HOL/document/root.tex

--- a/src/HOL/document/root.tex	Wed Dec 30 14:05:51 2015 +0100
+++ b/src/HOL/document/root.tex	Wed Dec 30 14:55:26 2015 +0100
@@ -1,6 +1,6 @@
-
 \documentclass[11pt,a4paper]{article}
 \usepackage{graphicx,isabelle,isabellesym,latexsym}
+\usepackage{amsmath}
 \usepackage{amssymb}
 \usepackage{textcomp}
 \usepackage[english]{babel}