Is there a simple and intuitive way to drawn with latex this kind of tree?
I tried to check in the site "LATEX for LOGICIANS", but I can't find this kind of tree, with this kind of layout. Thank you
-
2Section 4 of the LaTeX for Logicians site appears to have exactly this type of tree.– ThrustonDec 8, 2015 at 10:56
-
I saw it, but I would like to find the latex code of that kind of type...– MatteoDec 8, 2015 at 11:26
-
Well, if you look at the packages listed on that page, you will find plenty of examples. There are also examples on this site. This is just standard. You don't even need numbers or labelling, which is where the complications begin.– cfrDec 8, 2015 at 14:40
Add a comment
|
2 Answers
Here's a forest style, smullyan tableaux. The key closed can be used when the style is active to close the current branch.
One advantage of forest is the concise bracket syntax used to specify trees.
\documentclass[tikz,border=10pt]{standalone}
\newcommand*\lif{\mathbin{\to}}% added thanks to egreg's suggestion
\usepackage{forest}
\forestset{
smullyan tableaux/.style={
for tree={
math content
},
where n children=1{
!1.before computing xy={l=\baselineskip},
!1.no edge
}{},
closed/.style={
label=below:$\times$
},
},
}
\begin{document}
\begin{forest}
smullyan tableaux
[\lnot(\lnot(A \land B) \lif (\lnot A \lor \lnot B))
[\lnot(A \land B)
[\lnot(\lnot A \lor \lnot B)
[\lnot\lnot A
[\lnot\lnot B
[A
[B
[\lnot A, closed]
[\lnot B, closed]
]
]
]
]
]
]
]
\end{forest}
\end{document}
Note that it is more usual in logic, as far as I know, to draw trees so that branches start from a common point:
This can be achieved, if necessary, by adding
parent anchor=south,
child anchor=north,
to the style.
-
I usually define
\newcommand{\lto}{\mathbin{\to}}so the arrow is treated as a binary operation (which it is, in this case).– egregDec 8, 2015 at 22:45 -
@egreg I don't think it is really the correct arrow. When I had to draw these, I was using the horseshoe so it wasn't a problem.– cfrDec 9, 2015 at 0:58
-
@egreg Is that better? I think
\lifis better than\ltobecause it can be redefined to\supsetif necessary. (I know\ltocould be also, but\lifis semantic whereas\ltois format.)– cfrDec 9, 2015 at 1:08
Here is a simple code with pstricks, and more specifically with pst-tree:
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{mathtools}
\usepackage{pst-node, pst-tree, auto-pst-pdf}
\def\noedge{\ncline[linestyle = none]}
\renewcommand\psedge{\ncline[arrows =-]}
\begin{document}
\centering
\[ \psset{levelsep=1.2cm, treesep=2cm, nodesepA=10pt, nodesepB=2pt}
\pstree%
{\TR[vref =-1.25]{%
\makebox[0pt]{$ \begin{matrix}\neg(\neg(A\wedge B)\to(\neg A\vee\neg B))\\
\neg(A\wedge B)\\
\neg(\neg A\vee\neg B) \\
\neg\neg A\\
\neg\neg B\\
A\\B\end{matrix} $}}}%
{%
\TR[vref=1, href=2]{$ \begin{matrix} \neg A\\ \times\end{matrix}$}
\TR[vref=1, href=-2]{$ \begin{matrix} \neg B\\ \times \end{matrix}$}
} \]
\end{document}
