tables
In Exercise 22.7 of TeXbook, a special table is created using \halign with templates:
\def\welshverb#1={{\bf#1} = }
\halign{\welshverb#\hfil\tabskip=1em plus 1em&
\welshverb#\hfil&\welshverb#\hfil\tabskip=0pt\cr
rydw i=I am& ydw i=am I& roeddwn i=I was\cr
rwyt ti=thou art& wyt ti=art thou& roeddet ti=thou wast\cr
mae e=he is& ydy e=is he& roedd e=he was\cr
mae hi=she is& ydy hi=is she& roedd hi=she was\cr}
What's the easiest way to reproduce this table in modern LaTeX fashion?
You could define a thick version of \hline and a thick | as new column type as I did below. Both are based on the original code, only the thickness got changed from \arrayrulewidth to 1pt.
\documentclass[a4paper,png]{standalone}
\usepackage{array}
\makeatletter
\newcommand{\thickhline}{%
\noalign {\ifnum 0=`}\fi \hrule height 1pt
\futurelet \reserved@a \@xhline
}
\newcolumntype{"}{@{\hskip\tabcolsep\vrule width 1pt\hskip\tabcolsep}}
\makeatother
\begin{document}
\begin{tabular}{c"c|c|c|c|c}
$*$ & $a$ & $b$ & $c$ & $d$ & $e$ \\\thickhline
$a$ & $a$ & $b$ & $c$ & $b$ & $d$ \\\hline
$b$ & $b$ & $c$ & $a$ & $e$ & $c$ \\\hline
$c$ & $c$ & $a$ & $b$ & $b$ & $a$ \\\hline
$d$ & $b$ & $e$ & $b$ & $e$ & $d$ \\\hline
$e$ & $d$ & $b$ & $a$ & $d$ & $c$
\end{tabular}
\end{document}
On request here a definition of a thick version of \cline:
\newcommand{\thickcline}[1]{%
\@thickcline #1\@nil%
}
\def\@thickcline#1-#2\@nil{%
\omit
\@multicnt#1%
\advance\@multispan\m@ne
\ifnum\@multicnt=\@ne\@firstofone{&\omit}\fi
\@multicnt#2%
\advance\@multicnt-#1%
\advance\@multispan\@ne
\leaders\hrule\@height1pt\hfill
\cr
\noalign{\vskip-1pt}%
}
The idea is to use a combination of \multicolumn command (to add vertical lines in the table) together with the \cline command (to add horizontal lines):
\documentclass{article}
\usepackage{multirow}
\begin{document}
\begin{tabular}{ c c c c }
& & \multicolumn{2}{c}{Giocatore 2} \\
& & Sinistra & Centro \\ \cline{3-4}
\multirow{2}{*}{Giocatore 1} & Su & \multicolumn{1}{|c|}{1, 0} & \multicolumn{1}{|c|}{1, 2} \\ \cline{3-4}
& Giu & \multicolumn{1}{|c|}{0, 3} & \multicolumn{1}{|c|}{0, 1}\\ \cline{3-4}
\end{tabular}
\end{document}
The code produces the following table:
This Overleaf link is extremely useful when dealing with LaTex table formatting: https://www.overleaf.com/learn/latex/Tables
Best Answer
You can do even better, with an input syntax less crowded than Knuth's.