\documentclass[12pt,letterpaper]{article} \usepackage[utf8]{inputenc} \usepackage[english]{babel} \usepackage{amsthm} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{graphicx} \usepackage{array} \usepackage[left=2cm, right=2.5cm, top=2.5cm, bottom=2.5cm]{geometry} \usepackage{enumitem} \newcommand{\st}{\ \text{s.t.}\ } \newcommand{\abs}[1]{\left\lvert #1 \right\rvert} \newcommand{\R}{\mathbb{R}} \newcommand{\N}{\mathbb{N}} \newcommand{\Q}{\mathbb{Q}} \newcommand{\C}{\mathbb{C}} \newcommand{\Z}{\mathbb{Z}} \DeclareMathOperator{\sign}{sgn} \newtheoremstyle{case}{}{}{}{}{}{:}{ }{} \theoremstyle{case} \newtheorem{case}{Case} \theoremstyle{definition} \newtheorem{definition}{Definition}[section] \newtheorem{theorem}{Theorem}[section] \newtheorem{corollary}{Corollary}[section] \newtheorem{lemma}[theorem]{Lemma} \newtheorem*{remark}{Remark} \setlist[enumerate]{font=\bfseries} \renewcommand{\qedsymbol}{$\blacksquare$} \author{Alexander J. Tusa} \title{Real Analysis Homework 5} \begin{document} \maketitle \begin{enumerate} \end{enumerate} \end{document}