Vertically align possibly overlapping elements with different height. Placement of braces over parts of nested elements

Question

I want to vertically stack 3 elements (regular line width), braced with { (\left{) (equally aligned, so the 2nd element is aligned with the tip of the {), then draw an arrow out of the third element which will be at the center of another { brace containing 3 equally spaced lines. After that draw a } brace covering the two first elements of the first stacking and the first element of the nested stacking and nothing else.

Something like this

   {a     }
   {      }
...{b     }...
   {    {d}
   {c → {e
        {f

where vertically stacked '{' and '}' represent a big brace. I've tried using

\left\{
\begin{array}{l}
    \text{a} \\
    \text{b} \\
    \text{c} \left\{
    \begin{array}{l}
        \text{d}\\
        \text{e}\\
        \text{f}
    \end{array}
    \right.
\end{array}
\right.

for the first part but that ends up leaving more space for c thus making b not be vertically centered (so to not overlap). I also am not sure how to make the rightmost brace, tried some things with arrays and vphantom but couldn't get much to work

Answer 1

Welcome to TeX.SX! There are surely more elegant ways to do this, but maybe like this:

\documentclass{article}
\usepackage{amsmath}

\begin{document}
x\(\left\{
\begin{array}{@{}l@{}}
    \text{a} \\[1em]
    \text{b} \\[1em]
    \text{c}\rightarrow\smash{\left\{
    \begin{array}{@{}l@{}}
        \text{d} \\
        \text{e} \\
        \text{f}
    \end{array}
    \right.}
\end{array}
\right\}\)x
\end{document}

---

For more flexibility, for example if the right brace should already end at the "e", you can use the nicematrix package and add empty lines between "a" and "b" as well as between "b" and "c":

\documentclass{article}
\usepackage{amsmath}
\usepackage{nicematrix}

\begin{document}
x\(
\begin{NiceArray}{ll}[right-margin=1em, left-margin=1em, baseline=3]
    \text{a} &          \\
             &          \\
    \text{b} &          \\
             & \text{d} \\
    \text{c} \rightarrow 
             & \text{e} \\
             & \text{f} \\
\CodeAfter
    \SubMatrix{\lbrace}{1-1}{5-1}{.}
    \SubMatrix{.}{1-2}{4-2}{\rbrace}
    \SubMatrix{\lbrace}{4-2}{6-2}{.}
\end{NiceArray}\)x
\end{document}

---

And for even more flexibility, you can use TikZ for drawing the braces which even allows you to shift the tip of the right brace:

\documentclass{article}
\usepackage{amsmath}
\usepackage{nicematrix, tikz}
\usetikzlibrary{decorations.pathreplacing, calligraphy}

\begin{document}
x\(
\begin{NiceArray}{ll}[right-margin=1em, left-margin=1em, baseline=3]
    \text{a} &          \\
             &          \\
    \text{b} &          \\
             & \text{d} \\
    \text{c} \rightarrow 
             & \text{e} \\
             & \text{f} \\
\CodeAfter
    \begin{tikzpicture}
        \draw[decorate, very thick, decoration={calligraphic brace, amplitude=3.5, mirror}] 
            ([xshift=-.75ex]1-|1) -- ([xshift=-.75ex]6-|1);
        \draw[decorate, very thick, decoration={calligraphic brace, amplitude=3.5, aspect=0.625}] 
            ([xshift=.75ex]1-|3) -- ([xshift=.75ex]5-|3);
        \draw[decorate, very thick, decoration={calligraphic brace, amplitude=3.5, mirror}] 
            ([xshift=.5ex]4-|2) -- ([xshift=.5ex]7-|2);
    \end{tikzpicture}
\end{NiceArray}\)x
\end{document}