Nested left braces

Question

I am trying to write some sort of scheme using nested left braces, the code compiles however is throwing errors, I guess I am not closing the braces (I do not want them to be closed, only need left braces) so the compiler complaints. How could I fix this issue? Thank you very much in advance.

\documentclass[11pt, tikz]{article}
\usepackage{answers}
\usepackage{setspace}
\usepackage{graphicx}
\usepackage{slashbox}
\usepackage{enumitem}
\usepackage[colorlinks]{hyperref}
\usepackage{multicol}
\usepackage{booktabs}
\usepackage{amsmath}
\usepackage{mathrsfs}
\usepackage[table,x11names]{xcolor}
\usepackage[margin=1in]{geometry}
\usepackage{float}
\usepackage{amsmath,amsthm,amssymb}
\usepackage[utf8]{inputenc}
\usepackage {tikz}
\usepackage{multicol}
\usetikzlibrary{trees}
\usepackage{tikz-timing}[2014/10/29]
\usetikztiminglibrary[rising arrows]{clockarrows}
\usetikzlibrary {positioning}
\usepackage{xcolor}
\definecolor {processblue}{cmyk}{0.96,0,0,0}
\usepackage{caption}
\usepackage{array}
\newcolumntype{?}{!{\vrule width 2pt}}
\usepackage[spanish, es-tabla]{babel}
\makeatletter
\renewcommand{\@seccntformat}[1]{}
\makeatother
\setlength\parindent{24pt}
\usepackage{forest}
\usetikzlibrary{arrows.meta}
\begin{document}
[\text{Temperature}=\left{
\begin{array}{ll}
\text{Hot}  &
[\left{
\begin{array}{ll}
\text{No: 2}  & \
\text{Yes: 2} & \
\end{array} \
\text{Mild} &
[\left{
\begin{array}{ll}
\text{No: 2}  & \
\text{Yes: 4} & \
\end{array} \
\text{Cool} & 
[\left{
\begin{array}{ll}
\text{No: 1}  & \
\text{Yes: 3} & \
\end{array} \

\end{array} 
\right. ]
\end{document}

If the contents could be not only maths : texdoc schemata. An example here. — Fran, May 10 '21 at 20:37

score 5 · Answer 1 · answered May 10 '21 at 20:18

In my opinion, it is simpler to nest cases environments. Here is a possible code, with some layout improvements:

\documentclass{article}
\usepackage{amsmath}
\begin{document}
[
  \text{Temperature} = \begin{cases}
    \text{Hot} &
     \begin{cases}
        \text{No:} & 2\
        \text{Yes:} & 2
      \end{cases} \[2.5ex]
    \text{Mild} &
     \begin{cases}
        \text{No:} & 2 \
        \text{Yes:} & 4
      \end{cases}\[2.5ex]
    \text{Cool} &
      \begin{cases}
        \text{No:} & 1\
        \text{Yes:} & 3
      \end{cases} %\
  \end{cases}
]
\end{document}

score 4 · Answer 2 · answered May 10 '21 at 19:40

Correct. You have to close every opened \left-brace with an accompanying \right-brace within the same group. Here "brace" includes extensible braces like (, ), [, ], \{ and \} as well as the null delimiter ..

\documentclass{article}
\usepackage{amsmath}
\begin{document}
[
  \text{Temperature} = \left{\begin{array}{ll}
    \text{Hot}  &
      \left{\begin{array}{ll}
        \text{No: 2}  & \
        \text{Yes: 2} & \
      \end{array}\right. \
    \text{Mild} &
      \left{\begin{array}{ll}
        \text{No: 2}  & \
        \text{Yes: 4} & \
      \end{array}\right. \
    \text{Cool} & 
      \left{\begin{array}{ll}
        \text{No: 1}  & \
        \text{Yes: 3} & \
      \end{array}\right. \

  \end{array}\right.
]
\end{document}

score 2 · Answer 3 · answered May 10 '21 at 20:12

You shouldn't start \[ over and over again.

I present here a simpler syntax-wise code, at the expense of a not-so-easy definition.

\documentclass[11pt]{article}
\usepackage{amsmath,booktabs}
\newif\ifbtextinmath
\newenvironment{btext}[1]
 {% the conditional is initially false
  \btextinmathfalse
  % if btext is initiated in math mode, make the conditional true
  % otherwise start math mode
  \ifmmode\btextinmathtrue\else$\fi
  % left brace
  \left{
  % start a tabular
  \begin{tabular}{#1}%
 }
 {% end the tabular
  \end{tabular}%
  % null delimiter
  \right.%
  % if the conditional is true, do nothing; otherwise end math mode
  \ifbtextinmath\else$\fi
 }
\begin{document}
[
\text{Temperature}=
  \begin{btext}{@{}l@{\ }l@{}}
  Hot  &
    \begin{btext}{@{}l@{\ }l@{}}
      No: & 2 \
      Yes: & 2
    \end{btext} \
\addlinespace
  Mild &
    \begin{btext}{@{}l@{\ }l@{}}
      No: & 2 \
      Yes: & 4
    \end{btext} \
\addlinespace
  Cool &
    \begin{btext}{@{}l@{\ }l@{}}
      No: & 1 \
      Yes: & 3
    \end{btext}
  \end{btext}
]
\end{document}

The columns have been defined with no padding at the left and with a normal space between them. With booktabs facilities I added some vertical space between rows.

Nested left braces

3 Answers3