让我们考虑以下例子：
\documentclass[12pt,twoside,a4paper]{book}
\usepackage[left=.45in,right=.45in,top=.6in,bottom=.6in]{geometry}
\usepackage[fleqn]{amsmath}
\usepackage{amsfonts}
\usepackage{amsthm,amssymb,graphicx}
\usepackage[all]{xy}
\usepackage{graphicx,wrapfig,tikz}
\usepackage{enumerate}
\usepackage{fancyhdr}
\usetikzlibrary{positioning,decorations.markings}
\pagestyle{fancy}
\renewcommand{\chaptermark}[1]{\markboth{#1}{}}
\fancyhead{}
\fancyfoot{}
\fancyhead[LE,RO]{\thepage}
\fancyhead[LO]{\slshape\leftmark }
\fancyhead[RE]{\slshape Basic Algebraic Topology and its Applications}
\newtheoremstyle{myplain}% name
{3pt}% Space above
{3pt}% Space below
{\itshape}% Body font
{}% Indent amount
{\bfseries}% Theorem head font
{}% Punctuation after theorem head
{.5em}% Space after theorem head
{}% Theorem head spec (can be left empty, meaning `normal')
\theoremstyle{myplain}
\newtheorem{thm}{Theorem}[section]
\newtheorem{prop}[thm]{Proposition}
\newtheorem{defn}[thm]{Definition}
\newtheorem{example}[thm]{Example}
\newtheorem{lemma}[thm]{Lemma}
\newtheoremstyle{mytheoremm}% name
{3pt}% Space above
{3pt}% Space below
{\itshape}% Body font
{}% Indent amount
{\bfseries}% Theorem head font
{.}% Punctuation after theorem head
{.5em}% Space after theorem head
{}% Theorem head spec (can be left empty, meaning `normal')
\theoremstyle{mytheoremm}
\newtheorem{remark}{Remark}
\newtheorem*{remark*}{Remark}
\newtheorem{cor}{Corollary}
\newtheorem*{cor*}{Corollary}
\begin{document}
\setcounter{page}{0}\mbox{}\newpage
\thispagestyle{plain}
\def\chapternum{2}
\setcounter{chapter}{1}
\chapter{Homotopy}
\begin{thm}
Text.,...
\end{thm}
\begin{proof}
Text Text Text Text
\end{proof}
\end{document}
得出：
但我想制作：
即，框应该更粗。我该怎么做？
答案1
amsthmproof使用 as设置环境末尾的框\qedsymbol。 的默认值为，\qedsymbol其\openbox定义为
\newcommand{\openbox}{\leavevmode
\hbox to.77778em{%
\hfil\vrule
\vbox to.675em{\hrule width.6em\vfil\hrule}%
\vrule\hfil}}
此框中的规则（\hrule和）是。\vrule.4pt
一般来说，使用\renewcommand{\qedsymbol}{<whatever>}会将此符号切换为。以下是形式的<whatever>更新，设置一个类似于 的框，但线条粗细为：\openbox\OpenBox[<len>]\openbox<len>
\documentclass{article}
\usepackage{amsthm}% http://ctan.org/pkg/amsthm
\newcommand{\OpenBox}[1][.4pt]{\leavevmode
\hbox{% to.77778em{%
\hfil\vrule width#1
\vbox to.675em{\hrule width.6em height#1\vfil\hrule height#1}%
\vrule width#1\hfil}}
\begin{document}
\begin{minipage}{0.4\linewidth}
\begin{proof} This is a proof. \end{proof}
\renewcommand{\qedsymbol}{\OpenBox[.8pt]}
\begin{proof} This is a proof. \end{proof}
\renewcommand{\qedsymbol}{\OpenBox[1pt]}
\begin{proof} This is a proof. \end{proof}
\renewcommand{\qedsymbol}{\OpenBox[2pt]}
\begin{proof} This is a proof. \end{proof}
\end{minipage}
\end{document}
当然，最后一个并不好看，但它旨在向您展示加粗规则的含义。该框不是完美的正方形。但是，如果您使用的规则宽度是固定的，则\OpenBox可以调整里面的参数以使框变成正方形。
答案2
您的盒子相当大，因此可能需要类似以下的方法（A查看比例。设置尺寸后，所有内容均变成定义）：
A \rule{1mm}{4mm}\hspace{-1mm}\rule{4mm}{1mm}\hspace{-1mm}\rule{1mm}{4mm}\hspace{-4mm}\raisebox{3mm}{\rule{4mm}{1mm}}
