<!DOCTYPE para PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"> <para> Einstein's theory of relativity includes one of the most widely recognized formulas in the world: <inlineequation> <alt>e=mc^2</alt> <graphic fileref="figures/emc2.png"/> </inlineequation> </para>