防止支架下方的标签占用垂直空间

Question

\documentclass[12pt]{article}
\usepackage{amsmath}
\begin{document}
\begin{multline*}
= I_{B}(\Pi_{B})_{\theta}[\theta_{B},\Lambda^{\prime}[I_{0} - I_{B}[1-F(\theta_{B})]]] - I_{B}\Pi_{B}[\theta_{B},\Lambda^{\prime}[I_{0} - I_{B}[1- F(\theta_{B})]]] \times \cdots \\ \\
\cdots \times \frac{\left[ \everymath{\displaystyle}\setlength{\arraycolsep}{1.5pt} \begin{array}{l} (\Delta_{B})_{\theta}[\theta_{B},\Lambda^{\prime}[I_{0}-I_{B}[1-F(\theta_{B})]]] + f(\theta_{B}) \times \dots \hspace{0.75em} \\ \\
\multicolumn{1}{r}{\hspace{0.9em} \cdots\times [I_{0} - I_{B}[1-F(\theta_{B})]]\Lambda^{\prime\prime}[I_{0} - I_{B}[1-F(\theta_{B})]]}   \end{array} \right] }   {\left[\underbrace{\everymath{\displaystyle}\setlength{\arraycolsep}{1.5pt}    \begin{array}{l}
\Delta_{B}[\theta_{B},\Lambda^{\prime}[I_{0}-I_{B}[1-F(\theta_{B})]]] - [1- F(\theta_{B})]\times \cdots \\ \\
\multicolumn{1}{r}{\cdots\times[I_{0} - I_{B}[1-F(\theta_{B})]]\Lambda^{\prime\prime}[I_{0} - I_{B}[1-F(\theta_{B})]]}
\end{array}}_{<0 \text{ (see appendix)}} \right]} \leq 0,
\end{multline*}   
\end{document}

当 LaTeX 格式化方括号时，如何才能阻止标签< 0 \text{ (see appendix)}占用垂直空间？我一直在尝试\smash，但到目前为止还没有成功。

Answer 1

一个想法是省略分数中的括号。另一个想法是给整个矩阵加底线，假装它比实际要小：

\documentclass[12pt]{article}
\usepackage{amsmath}

\begin{document}

\begin{multline*}
= I_{B}(\Pi_{B})_{\theta}[\theta_{B},\Lambda'[I_{0} - I_{B}[1-F(\theta_{B})]]] 
  - I_{B}\Pi_{B}[\theta_{B},\Lambda'[I_{0} - I_{B}[1- F(\theta_{B})]]] \times {}
\\[1ex]
{} \times 
  \frac{
    \begin{bmatrix}
    (\Delta_{B})_{\theta}[\theta_{B},\Lambda'[I_{0}-I_{B}[1-F(\theta_{B})]]]
     + f(\theta_{B}) \times {}\qquad \hfill
    \\[1ex]
    \hfill\qquad{}\times [I_{0} - I_{B}[1-F(\theta_{B})]]\Lambda''[I_{0} - I_{B}[1-F(\theta_{B})]]
    \end{bmatrix}
  }{
    \mspace{12mu}
    \underbrace{
      \mspace{-12mu}\begin{bmatrix}
      \Delta_{B}[\theta_{B},\Lambda'[I_{0}-I_{B}[1-F(\theta_{B})]]]
        - [1- F(\theta_{B})]\times {}\qquad\hfill
      \\[1ex]
      \hfill\qquad{}\times[I_{0} - I_{B}[1-F(\theta_{B})]]\Lambda''[I_{0} - I_{B}[1-F(\theta_{B})]]
      \end{bmatrix}\mspace{-12mu}
    }_{<0 \text{ (see appendix)}}
    \mspace{12mu}
  } \leq 0,
\end{multline*}   

\end{document}

我做了一些简化（例如用'和''代替^{\prime}和^{\prime\prime}。我还删除了从未用于表示“暂停”操作的点，而是省略了术语。

Answer 2

基于@egreg 的想法，但改用from splitfrac。为了使代码更简短，我删除了索引周围的花括号。mathtoolsbmatrix

\documentclass[12pt]{article}
    \usepackage{mathtools}
\usepackage[active,displaymath,tightpage]{preview}
\setlength\PreviewBorder{5pt}%

\begin{document}
    \begin{multline*}
= I_{B}(\Pi_{B})_{\theta}[\theta_{B},\Lambda'[I_{0} - I_{B}[1-F(\theta_{B})]]]
  - I_{B}\Pi_{B}[\theta_{B},\Lambda'[I_{0} - I_{B}[1- F(\theta_{B})]]]              \\[1ex]
%
\times\frac{\left[
\splitfrac{(\Delta_B)_\theta[\theta_B,\Lambda'[I_0-I_B[1-F(\theta_B)]]] + f(\theta_B)}
          {\times [I_0 - I_{B}[1-F(\theta_B)]]\Lambda''[I_0 - I_B[1-F(\theta_B)]]}\right]
            }{\underbrace{\mspace{-12mu}\left[
\splitfrac{\Delta_B[\theta_B,\Lambda'[I_{0}-I_B[1-F(\theta_B)]]] - [1- F(\theta_B)]}
          {\times[I_0 - I_B[1-F(\theta_B)]]\Lambda''[I_0 - I_B[1-F(\theta_B)]]}\right]\mspace{-12mu}
                          }_{<0 \text{ (see appendix)}}
             } \leq 0,
    \end{multline*}
\end{document}