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将列表中的文本对齐，每行开头使用不同长度的文本

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将列表中的文本对齐，每行开头使用不同长度的文本

对于我的离散结构类，我经常发现自己创建包含方程式或命题陈述的列表，并且在同一行但更靠右的位置需要描述。我想对齐所有描述，即使方程式或命题的长度可能都不同。我还没有看到适用于此特定问题的任何对齐问题解决方案。下图显示了我正在寻找的内容以及问题（我已经使用 \hspace{} 手动对齐了前 7 行，但想要一个更简单的解决方案，因为您可以看到即使手动执行也无法完美对齐）。

在此处输入图片描述

答案1

您可以吸收适当材料以表格形式输入并测量列宽。

\documentclass{article}
\usepackage{amsmath}

\usepackage{lipsum}

\ExplSyntaxOn

\NewDocumentEnvironment{formalproof}{b}
 {
  \begin{flushleft}
  \linespread{1.2}\selectfont
  \james_formalproof:n { #1 }
  \end{flushleft}
 }
 {}

\seq_new:N \l__james_formalproof_body_seq
\seq_new:N \l__james_formalproof_tmp_seq
\dim_new:N \l__james_formalproof_left_dim
\dim_new:N \l__james_formalproof_right_dim
\dim_new:N \l__james_formalproof_step_dim
\int_new:N \l__james_formalproof_line_int

\cs_new_protected:Nn \james_formalproof:n
 {
  \seq_set_split:Nnn \l__james_formalproof_body_seq { \\ } { #1 }
  % check for a trailing \\
  \seq_pop_right:NN \l__james_formalproof_body_seq \l_tmpa_tl
  \tl_if_blank:VF \l_tmpa_tl
   {% the last item is not empty, restore it
    \seq_put_right:NV \l__james_formalproof_body_seq \l_tmpa_tl
   }
  % now let's compute the item widths
  \dim_zero:N \l__james_formalproof_left_dim
  \dim_zero:N \l__james_formalproof_right_dim
  \seq_map_inline:Nn \l__james_formalproof_body_seq
   {
    \seq_set_split:Nnn \l__james_formalproof_tmp_seq { & } { ##1 }
    \hbox_set:Nn \l_tmpa_box { $\seq_item:Nn \l__james_formalproof_tmp_seq { 1 }$ }
    \dim_set:Nn \l__james_formalproof_left_dim
     {
      \dim_max:nn { \l__james_formalproof_left_dim } { \box_wd:N \l_tmpa_box }
     }
    \hbox_set:Nn \l_tmpb_box { (\seq_item:Nn \l__james_formalproof_tmp_seq { 2 }) }
    \dim_set:Nn \l__james_formalproof_right_dim
     {
      \dim_max:nn { \l__james_formalproof_right_dim } { \box_wd:N \l_tmpb_box }
     }
   }
  \hbox_set:Nn \l_tmpa_box { \seq_count:N \l__james_formalproof_body_seq }
  \dim_set:Nn \l__james_formalproof_step_dim { \box_wd:N \l_tmpa_box }
  % now we can process the whole thing
  \int_zero:N \l__james_formalproof_line_int
  \seq_map_inline:Nn \l__james_formalproof_body_seq
   {
    \seq_set_split:Nnn \l__james_formalproof_tmp_seq { & } { ##1 }
    \int_incr:N \l__james_formalproof_line_int
    \par
    \makebox[\l__james_formalproof_step_dim][r]
     { \int_to_arabic:n { \l__james_formalproof_line_int } }.\enspace
    \makebox[\l__james_formalproof_left_dim][l]
     { $\seq_item:Nn \l__james_formalproof_tmp_seq { 1 }$ }
    \hfill
    \makebox[\l__james_formalproof_right_dim][l]
     { (\seq_item:Nn \l__james_formalproof_tmp_seq { 2 }) }
   }
 }

\ExplSyntaxOff

\begin{document}

\lipsum[2][1-4]

\begin{formalproof}
\exists x \overline{A(x)} & premise \\
\overline{A(a)} & existential instantiation \\
\forall x(C(x)\to\overline{D(x)}) & premise \\
C(a)\to\overline{D(a)} & universal instantiation \\
\overline{C(a)}\lor \overline{D(a)} & definition \\
\forall x(\overline{B(x)}\lor D(x)) & premise \\
\overline{B(a)}\lor D(a) & universal instantiation \\
\overline{C(a)}\lor\overline{B(a)} & resolution 5+7 \\
\forall x(A(x)\lor B(x)) & premise
\end{formalproof}

\lipsum[3][1-4]

\begin{formalproof}
\exists x \overline{A(x)} & premise \\
\overline{A(a)} & existential instantiation \\
\forall x(C(x)\to\overline{D(x)}) & premise \\
C(a)\to\overline{D(a)} & universal instantiation \\
\overline{C(a)}\lor \overline{D(a)} & definition \\
\forall x(\overline{B(x)}\lor D(x)) & premise \\
\overline{B(a)}\lor D(a) & universal instantiation \\
\overline{C(a)}\lor\overline{B(a)} & resolution 5+7 \\
\forall x(A(x)\lor B(x)) & premise \\
A+B+C & just one more line \\
\end{formalproof}

\lipsum[4][1-3]

\end{document}

在第二个例子中，您会看到两件事：为数字保留的宽度得到了照顾；此外，尾随\\没有任何影响。

在此处输入图片描述

请注意，这允许在正式证明中分页。另一种方法是使用tabular*：

\documentclass{article}
\usepackage{amsmath}
\usepackage{array}

\usepackage{lipsum}

\ExplSyntaxOn

\NewDocumentEnvironment{formalproof}{b}
 {
  \james_formalproof:n { #1 }
 }
 {}

\seq_new:N \l__james_formalproof_body_seq
\int_new:N \g__james_formalproof_line_int

\cs_new_protected:Nn \james_formalproof:n
 {
  \renewcommand{\arraystretch}{1.2}
  \setlength{\tabcolsep}{0pt}
  \seq_set_split:Nnn \l__james_formalproof_body_seq { \\ } { #1 }
  % check for a trailing \\
  \seq_pop_right:NN \l__james_formalproof_body_seq \l_tmpa_tl
  \tl_if_blank:VF \l_tmpa_tl
   {% the last item is not empty, restore it
    \seq_put_right:NV \l__james_formalproof_body_seq \l_tmpa_tl
   }
  % process the material in a tabular*
  \int_gzero:N \g__james_formalproof_line_int
  \begin{tabular*}{\textwidth}
   {
    >{
      \int_gincr:N \g__james_formalproof_line_int
      \int_to_arabic:n { \g__james_formalproof_line_int }
      .
    }r
    @{\hspace{0.5em}}
    >{$}l<{$}
    @{\extracolsep{\fill}}
    >{(}l<{)}
    @{}
   }
  \seq_map_function:NN \l__james_formalproof_body_seq \__james_formalproof_line:n
  \end{tabular*}
 }

\cs_new:Nn \__james_formalproof_line:n { & #1 \\ }

\ExplSyntaxOff

\begin{document}

\lipsum[2][1-4]

\begin{center}
\begin{formalproof}
\exists x \overline{A(x)} & premise \\
\overline{A(a)} & existential instantiation \\
\forall x(C(x)\to\overline{D(x)}) & premise \\
C(a)\to\overline{D(a)} & universal instantiation \\
\overline{C(a)}\lor \overline{D(a)} & definition \\
\forall x(\overline{B(x)}\lor D(x)) & premise \\
\overline{B(a)}\lor D(a) & universal instantiation \\
\overline{C(a)}\lor\overline{B(a)} & resolution 5+7 \\
\forall x(A(x)\lor B(x)) & premise
\end{formalproof}
\end{center}

\lipsum[3][1-4]

\begin{center}
\begin{formalproof}
\exists x \overline{A(x)} & premise \\
\overline{A(a)} & existential instantiation \\
\forall x(C(x)\to\overline{D(x)}) & premise \\
C(a)\to\overline{D(a)} & universal instantiation \\
\overline{C(a)}\lor \overline{D(a)} & definition \\
\forall x(\overline{B(x)}\lor D(x)) & premise \\
\overline{B(a)}\lor D(a) & universal instantiation \\
\overline{C(a)}\lor\overline{B(a)} & resolution 5+7 \\
\forall x(A(x)\lor B(x)) & premise \\
A+B+C & just one more line \\
\end{formalproof}
\end{center}

\lipsum[4][1-3]

\end{document}

输出基本与以前相同。

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