\documentclass{article}
%% Page layout
\usepackage{geometry}
\geometry{letterpaper,total={5.0in,9in}}
%% Symbols, align environment, bracket-matrix
\usepackage{amsmath}
%% Theorem-like environments
\usepackage{amsthm}
\newtheorem{theorem}{Theorem}
\newtheorem{corollary}{Corollary}
\newtheorem{lemma}{Lemma}
%% Convenience macros
%% Title information
\title{}
\author{\\
\texttt{}\\
\\
}
\date{}
\begin{document}
\maketitle
\end{document}
\begin{theorem}
\end{theorem}
%
\begin{corollary}
\end{corollary}
%
\begin{lemma}
\end{lemma}
%
\begin{proof}
\end{proof}
%
\par
%
\(\)
\[\]
\begin{align*}\end{align*}
\begin{enumerate}
\end{enumerate}
%
\begin{itemize}
\end{itemize}
%
\item