-\documentclass[a4paper]{article}
+\documentclass[a4paper,leqno]{strayman}
+\let\numberwithin=\notdef
+\usepackage{txfonts}
\begin{document}
-$ \{ B \} $
+${\varmathbb Q}$
+\section{Section}
+\subsection{Subsection $\varmathbb P$ breaks}
+body
\end{document}