3

I'm wondering if it exists a canonical/natural/smooth/economical way of drawing such a diagram

enter image description here

for the definition of a function. The best I managed to do with tikz and align is very poor. I'm a beginner with Latex, hence I apologize in advance in case the question had a trivial answer.

6

Welcome to TeX.SE! If you want just this alignment, you only need an array.

\documentclass{article}
\usepackage{amsmath}
\usepackage{mathrsfs}
\begin{document}
\[
 \begin{array}{ccc}
  \mathscr{A}(B,C)\times\mathscr{A}(A,B) & \to & \mathscr{A}(A,C)\;,\\
  (g,f) & \mapsto & g\circ f\;,
 \end{array}
\]
\end{document}

enter image description here

3

Here is a solution based on align* and eqparbox. I added two variants which look nicer, from my point of view. The last one doesn't require eqparbox:

    \documentclass{article}
    \usepackage{amsmath}
    \usepackage{mathrsfs}
    \usepackage{eqparbox}
    \newcommand{\eqmathbox}[2][M]{\eqmakebox[#1]{$\displaystyle#2$}}

    \begin{document}

     \begin{align*}
      \eqmathbox{\mathscr{A}(B,C)\times\mathscr{A}(A,B)} & \longrightarrow \eqmathbox[R]{\mathscr{A}(A,C)}\;,\\
      \eqmathbox{(g,f)} & \longmapsto \eqmathbox[R]{g\circ f}\;,
     \end{align*}

     \begin{align*}
\mathscr{A}(B,C)\times \eqmathbox[L]{\mathscr{A}(A,B)} & \longrightarrow \eqmathbox[R]{\mathscr{A}(A,C)}\;,\\
      \eqmathbox[L]{(g,f)} & \longmapsto \eqmathbox[R]{g\circ f}\;,
     \end{align*}


     \begin{align*}
     \mathscr{A}(B,C)\times\mathscr{A}(A,B) & \longrightarrow \mathscr{A} (A,C)\;,\\
      (g,f) & \longmapsto g\circ f\;,
     \end{align*}

    \end{document}

enter image description here

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.