在 ntheorem 框架环境中更改 qedsymbol 和字体形状

Question

早上好：经过大量证明，按照 ntheorem 包和其他包的文档中的建议更改变量和参数后，我无法用 \blacksquare 替换 qedsymbol，也无法将定理正文字体的形状更改为常规形状（非斜体）。有人能帮帮我吗？谢谢！

来源如下。

\documentclass[a4paper,11pt]{book}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}
\usepackage[english]{babel}
\usepackage{amssymb} % Conjunto de símbolos matemáticos
%\usepackage{amsthm}  % Formato para enunciados y demostraciones
\usepackage{amsmath}
\usepackage{enumitem}
\usepackage{framed}
\usepackage{pstricks}
%
\usepackage[amsthm,thmmarks,framed]{ntheorem}
\theoremseparator{:}
\newtheorem{Theorem}{Theorem}
\theoremstyle{plain}
%
\newtheorem{Proposition}{Proposition}
%
\newframedtheorem{importantTheorem}[Theorem]{Theorem}
%
\newframedtheorem{importantProp}[Proposition]{Proposition}
%
\theorembodyfont{\normalfont\bfseries}
%
\renewcommand{\qedsymbol}{$\blacksquare$}
%\theoremsymbol{\ensuremath{_\blacksquare}}
%
\begin{document}
\chapter{First chapter}
% Main text
Blabla bla The above properties carry over to all subsequent newtheorem statements
until they are set differently. Initially, they have default values.
The following two properties apply only to the very next newtheorem and
are then automatically reset:
%
\begin{Theorem}
The above properties carry over to all subsequent newtheorem statements
until they are set differently. Initially, they have default values.
The following two properties apply only to the very next newtheorem and
are then automatically reset: blablabla
\end{Theorem}
%
Bla bla bla bla
%
\begin{proof}
The above properties carry over to all subsequent newtheorem statements
until they are set differently. Initially, they have default values.
The following two properties apply only to the very next newtheorem and
are then automatically reset:
\end{proof}
%
\begin{importantTheorem}[Important Theorem]
The above properties carry over to all subsequent newtheorem statements
until they are set differently. Initially, they have default values.
The following two properties apply only to the very next newtheorem and
are then automatically reset:
\end{importantTheorem}
%
\begin{importantProp}[Important Proposition]
This is an important theorem.
The above properties carry over to all subsequent newtheorem statements
until they are set differently. Initially, they have default values.
The following two properties apply only to the very next newtheorem and
are then automatically reset:
\end{importantProp}
%
\end{document}

Answer 1

欢迎使用 TeX SX！您的问题来自使用该amsthm选项。这是一个解决方案（我不确定是否完全理解了您的所有问题，因此如果这不是您想要的，请告诉我）：

    \documentclass[a4paper,11pt]{book}
    \usepackage[T1]{fontenc}
    \usepackage[utf8]{inputenc}
    \usepackage{lmodern}
    \usepackage[english]{babel}
    \usepackage{amssymb} % Conjunto de símbolos matemáticos
    %\usepackage{amsthm} % Formato para enunciados y demostraciones
    \usepackage{amsmath}
    \usepackage{enumitem}
    \usepackage{framed}
    \usepackage{pstricks}
    %
    \usepackage[thmmarks,framed]{ntheorem}%

    \theoremseparator{:}
    \theoremstyle{plain}
    \theoremheaderfont{\normalfont\bfseries}
    \theorembodyfont{\upshape}
    %
    \newtheorem{Theorem}{Theorem}
    \newtheorem{Proposition}{Proposition}
    %
    \newframedtheorem{importantTheorem}[Theorem]{Theorem}
    %
    \newframedtheorem{importantProp}[Proposition]{Proposition}

    %
    \theoremstyle{nonumberplain}
    \theoremheaderfont{\itshape}
    \theorembodyfont{\upshape}
    \theoremsymbol{$\blacksquare$}
    \newtheorem{proof}{Proof}
    %
    \begin{document}
    \chapter{First chapter}
    % Main text
    Blabla bla The above properties carry over to all subsequent newtheorem statements
    until they are set differently. Initially, they have default values.
    The following two properties apply only to the very next newtheorem and
    are then automatically reset:
    %
    \begin{Theorem}
    The above properties carry over to all subsequent newtheorem statements
    until they are set differently. Initially, they have default values.
    The following two properties apply only to the very next newtheorem and
    are then automatically reset: blablabla
    \end{Theorem}
    %
    Bla bla bla bla
    %
    \begin{proof}
    The above properties carry over to all subsequent newtheorem statements
    until they are set differently. Initially, they have default values.
    The following two properties apply only to the very next newtheorem and
    are then automatically reset:
    \end{proof}
    %
    \begin{importantTheorem}[Important Theorem]
    The above properties carry over to all subsequent newtheorem statements
    until they are set differently. Initially, they have default values.
    The following two properties apply only to the very next newtheorem and
    are then automatically reset:
    \end{importantTheorem}
    %
    \begin{importantProp}[Important Proposition]
    This is an important theorem.
    The above properties carry over to all subsequent newtheorem statements
    until they are set differently. Initially, they have default values.
    The following two properties apply only to the very next newtheorem and
    are then automatically reset:
    \end{importantProp}
    %
    \end{document}