将符号置于关系之上而不改变上标的位置

将符号置于关系之上而不改变上标的位置

我想在关系上放置一个符号,而不改变上标的位置。

\documentclass{article}
\usepackage{mathtools}
\usepackage{amssymb}
\usepackage{accents}

\newcommand{\rel}{\rhd}
\newcommand{\symb}{\text{I}}

\newcommand{\testmyrel}[1]{%
  \begin{center}%
  \begin{minipage}{\linewidth/2}%
    \noindent Text text text\\%
    $\text{T} #1^* \text{U}$\\%
    $\text{T} \rel^* \text{U}$\\%
  \end{minipage}%
  \end{center}%
}%

\begin{document}
    
My goal is to place a symbol (e.g. $\symb$) over a rel (e.g. $\rel$) that can be used in text without overlapping with text above, and handles superscripts as if it did not have a symbol:
\begin{center}%
    \begin{minipage}{\linewidth/2}%
        \noindent Text text text\\%
        $\text{T} \mathrel{\overset{\symb}{\rel}\vphantom{\rel}^*} \text{U}$\\%
        $\text{T} \rel^* \text{U}$\\%
    \end{minipage}%
\end{center}%

However, I do not want the superscript to be an argument of the command, which rules out the code above.

\begin{itemize}

\item Using overset makes the star too high:%
    \testmyrel{%
        \mathrel{%
            \overset{%
                \symb%
            }{%
                \mathord{\rel}%
            }%
        }%
    }%
%
\item Smashing the rel makes it go over the text:%
    \testmyrel{%
        \mathrel{%
            \smash{
                \overset{\symb}{\mathord{\rel}}%
            }%
        }%
    }%
%
\item Smashing the symbol makes it go over the text:%
\testmyrel{%
    \mathrel{%
        \overset{%
            \smash{\symb}%
        }{%
            \mathord{\rel}%
        }%
    }%
}%
%
\item Adding a vphantom inside mathrel leads to the star being too high:%
    \testmyrel{%
        \mathrel{%
            \overset{\symb}{\mathord{\rel}}%
            \vphantom{\symb}%
        }%
    }%
%
\item Adding a vphantom after mathrel leads to the star being misplaced to the right:%
\testmyrel{%
    \mathrel{%
        \overset{\symb}{\mathord{\rel}}%
    }%
    \vphantom{\symb}%
}%

\item Accentset without mathrel does not have the spacing due to mathrel:
\testmyrel{%
    \accentset{\symb}{\mathord{\rel}}%
}%

\item Accentset with mathrel puts the star too high:
\testmyrel{%
    \mathrel{\accentset{\symb}{\mathord{\rel}}}%
}%
\end{itemize}

\end{document}

答案1

不要\text在数学中用它以直立类型排版,它通常不起作用;使用\mathrm

也是\rhd不是一个关系符号,但做到这一点并不难。

\documentclass{article}
\usepackage{amsmath,amssymb,accents}

% \rhd is not a relation symbol
\mathchardef\rel=\numexpr\rhd+"1000

\newcommand{\overrel}[2]{%
  \mathrel{\accentset{#1}{#2}}%
  \mathrel{\vphantom{#2}}%
}

\begin{document}

\begin{center}
Text text text\\
$T \overrel{\mathrm{I}}{\rel}^* U$\\
$T \rel^* U$
\end{center}

\end{document}

在此处输入图片描述

或者,使用\overset

\newcommand{\overrel}[2]{%
  \overset{#1}{#2}%
  \mathrel{\vphantom{#2}}%
}

在此处输入图片描述

诀窍在于,TeX 不会在连续的关系原子之间添加空格,也不会添加换行点。因此,我们可以将下标/上标添加到幻影关系中。

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