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标签名称不以数字开头

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标签名称不以数字开头

我目前正在编写一些 MIP 求解器基准库的文档。这包括每种问题类型的描述。例如，对于 binpacking，我有

\section{Bin Packing Problem}\label{bpp}

\subsection{Formulation}
We are given $n$ items in an item set $I$ with weights $w_i$, with $i \in I$. 
The items shall be packed into bins (also $n$ many, but we use $B$ as the set 
of bins for the sake of readability) with capacity $C$ such that the number of 
bins used is minimal. We use two types of variables:
\begin{itemize}
  \item $x_{ij} \in \{0, 1\}$ should be $1$ iff item $i$ is packed into bin $j$.
  \item $y_j \in \{0, 1\}$ should be $1$ iff bin $j$ is used.
\end{itemize}
\begin{align}
  \text{minimize }      & \sum_{j \in B} y_j                                            \label{bpp:obj}\\
  \text{subject to }    & \sum_{j \in B} x_{ij} = 1             & i \in I               \label{bpp:setpp}\\
                        & \sum_{i \in I} w_i x_{ij} \leq C y_j  & j \in B               \label{bpp:capacity}\\
                        & x_{ij} \in \{0, 1\}                   & i \in I, j \in B\\
                        & y_j \in \{0, 1\}                      & j \in B
\end{align}

如您所见，目标函数和每个约束都有一个标签。现在，假设这个装箱部分是第 1 部分。因此，标签被命名为 (1.1)、(1.2)、(1.3)。但我希望它们有一个像 (BPP.1)、(BPP.2)、(BPP.3) 这样的名称，即底层问题的一些常见缩写。但是，该部分本身仍应有一个用于目录和其他参考资料的编号。

有什么建议可以实现这一点吗？

答案1

您可以定义样式设置\theequation：

\renewcommand{\theequation}{BPP.\arabic{equation}}

这将产生名为(BPP.1)、(BPP.2)等的标签。

要在文档中使用它，我建议使用宏来设置样式，如下所示：

\newcounter{oldeq}
\newcommand{\setpreeqno}[1]{% set text before equation number
  \ifx\preeqno\empty% if no preeqno was given before
    \def\preeqno{#1}% set to argument
    \ifx\preeqno\empty\else% if an argument was given
      \renewcommand{\theequation}{#1.\arabic{equation}}% set to "arg.#"
      \setcounter{oldeq}{\value{equation}}% save equation counter
      \setcounter{equation}{0}% reset locally to start with "arg.1"
    \fi%
  \else%
    \def\preeqno{#1}% set to argument
    \ifx\preeqno\empty% if no argument was given
      \renewcommand{\theequation}{\arabic{equation}}% reset to default arabic number
      \setcounter{equation}{\value{oldeq}}% continue counting
    \else%
      \renewcommand{\theequation}{#1.\arabic{equation}}% set to "arg.#"
      \setcounter{equation}{0}% reset locally to start with "arg.1"
    \fi%
  \fi%
  \ignorespaces%
}

或者在完整的 MWE 中：

\documentclass{article}
\usepackage{amsmath}


\newcounter{oldeq}
\newcommand{\setpreeqno}[1]{% set text before equation number
  \ifx\preeqno\empty% if no preeqno was given before
    \def\preeqno{#1}% set to argument
    \ifx\preeqno\empty\else% if an argument was given
      \renewcommand{\theequation}{#1.\arabic{equation}}% set to "arg.#"
      \setcounter{oldeq}{\value{equation}}% save equation counter
      \setcounter{equation}{0}% reset locally to start with "arg.1"
    \fi%
  \else%
    \def\preeqno{#1}% set to argument
    \ifx\preeqno\empty% if no argument was given
      \renewcommand{\theequation}{\arabic{equation}}% reset to default arabic number
      \setcounter{equation}{\value{oldeq}}% continue counting
    \else%
      \renewcommand{\theequation}{#1.\arabic{equation}}% set to "arg.#"
      \setcounter{equation}{0}% reset locally to start with "arg.1"
    \fi%
  \fi%
  \ignorespaces%
}


\begin{document}
\thispagestyle{empty}
\section{Bin Packing Problem}\label{bpp}\setpreeqno{BPP}

\subsection{Formulation}
We are given $n$ items in an item set $I$ with weights $w_i$, with $i \in I$. 
The items shall be packed into bins (also $n$ many, but we use $B$ as the set 
of bins for the sake of readability) with capacity $C$ such that the number of 
bins used is minimal. We use two types of variables:
\begin{itemize}
  \item $x_{ij} \in \{0, 1\}$ should be $1$ iff item $i$ is packed into bin $j$.
  \item $y_j \in \{0, 1\}$ should be $1$ iff bin $j$ is used.
\end{itemize}
\begin{align}
  \text{minimize }      & \sum_{j \in B} y_j                                            \label{bpp:obj}\\
  \text{subject to }    & \sum_{j \in B} x_{ij} = 1             & i \in I               \label{bpp:setpp}\\
                        & \sum_{i \in I} w_i x_{ij} \leq C y_j  & j \in B               \label{bpp:capacity}\\
                        & x_{ij} \in \{0, 1\}                   & i \in I, j \in B\\
                        & y_j \in \{0, 1\}                      & j \in B
\end{align}

This reference looks like \eqref{bpp:obj}.
\end{document}

在此处输入图片描述

编辑我通过处理全局计数器改进了代码（受到@egreg 的回答的启发）

答案2

subequations使用相同基础设施的变体。

\documentclass{article}
\usepackage{amsmath}

\newenvironment{labeledequations}[1]{%
  \setcounter{parentequation}{\value{equation}}%
  \setcounter{equation}{0}%
  \def\theequation{#1.\arabic{equation}}%
  \ignorespaces
}{%
  \setcounter{equation}{\value{parentequation}}%
  \ignorespacesafterend
}


\begin{document}

\section{Bin Packing Problem}\label{bpp}

\subsection{Formulation}
We are given $n$ items in an item set $I$ with weights $w_i$, with $i \in I$. 
The items shall be packed into bins (also $n$ many, but we use $B$ as the set 
of bins for the sake of readability) with capacity $C$ such that the number of 
bins used is minimal. We use two types of variables:
\begin{itemize}
  \item $x_{ij} \in \{0, 1\}$ should be $1$ iff item $i$ is packed into bin $j$.
  \item $y_j \in \{0, 1\}$ should be $1$ iff bin $j$ is used.
\end{itemize}
\begin{labeledequations}{BPP}
\begin{align}
\text{minimize }   & \sum_{j \in B} y_j 
  \label{bpp:obj} \\
\text{subject to } & \sum_{j \in B} x_{ij} = 1             && i \in I
  \label{bpp:setpp} \\
                   & \sum_{i \in I} w_i x_{ij} \leq C y_j  && j \in B
  \label{bpp:capacity} \\
                   & x_{ij} \in \{0, 1\}                   && i \in I, j \in B
  \\
                   & y_j \in \{0, 1\}                      && j \in B
\end{align}
\end{labeledequations}

The references to \eqref{bpp:obj} and \eqref{bpp:capacity} are correct.

\end{document}

在此处输入图片描述

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