如何仅为实例创建章节名称

Question

因此，我有此章节名称，其标准名称为：

Chapter 1
Chapter 2
Chapter 3

但我想要一个完全不同的章节名称，可以称为：Category

并且它将与其他章节名称共存，而不会发生任何改变，如下所示：

Chapter 1
Chapter 2 
Chapter 3+4
Category
Chapter 9

这是我的代码和尝试：

%% document class and packages
\documentclass[12pt,a4paper]{report}
\usepackage[utf8]{inputenc}
\usepackage{titlesec}
\usepackage{fancyhdr}

%% titlesec
\titleformat{\chapter}[hang]
    {\normalfont\huge\bfseries}
    {\chaptertitlename\ \thechapter: }
    {0em}
    {\centering} 
\titlespacing*{\chapter}{0pt}{-40pt}{20pt}
\titlelabel{\thetitle.\quad}
\titleformat{\subsubsection}[runin]
  {\normalfont\large\bfseries}{\thesubsubsection}{1em}{}

%% Attempt to make a command
\newcommand\categorychapter{\setchapter{Chủ đề:}}
%% Default chapter settings
\AtBeginDocument{\renewcommand{\chaptername}{Bài}}
\linespread{1.05}
\raggedbottom

\begin{document}

\chapter{First Chapter}

\chapter{Second Chapter}

%% Double numbered chapter
\label{single}
\let\oldchapter\thechapter
\def\thechapter{\arabic{chapter}\texttt{+}\the\numexpr\value{chapter}+1\relax}
\chapter{Chapter three plus four}

%% Chapter returning to normal numbering after skipping a number
\label{double}
\let\thechapter\oldchapter
\refstepcounter{chapter}
\refstepcounter{chapter}
\chapter{Chapter six}

%% Regular chapter without any alterations
\chapter{Chapter seven}

%% Attempt at a special chapter
\categorychapter{Category Chapter}
%% Radically different chapter numbering 
\setcounter{chapter}{11}
\chapter{Chapter twelve}

Answer 1

我不确定我是否理解正确，但使用\chapter*{Category}可能就能解决它？

%% document class and packages
\documentclass{report}

\begin{document}

\chapter{First Chapter}

\chapter{Second Chapter}

%% Double numbered chapter
\label{single}
\let\oldchapter\thechapter
\def\thechapter{\arabic{chapter}\texttt{+}\the\numexpr\value{chapter}+1\relax}
\chapter{Chapter three plus four}

%% Chapter returning to normal numbering after skipping a number
\label{double}
\let\thechapter\oldchapter
\refstepcounter{chapter}
\refstepcounter{chapter}
\chapter{Chapter six}

%% Regular chapter without any alterations
\chapter{Chapter seven}

%% Attempt at a special chapter
\chapter*{Category Chapter}
%% Radically different chapter numbering 
\setcounter{chapter}{11}
\chapter{Chapter twelve}
\end{document}