# Unusual bussproofs derivation

I'm trying to typeset proofs like these in bussproofs (to keep them consistent with the rest of my proofs) but I can't figure out a good way to do so:

I've tried using various combinations of \rootAtTop to almost no success (e.g. I'm unable to add the second pair of vdots in the first derivation without messing everything up; letters I'm the second derivation fall off their lines and don't align).

(1)

    \AxiomC{$A$} \noLine
\UnaryInfC{$\strut \vdots$}
\rootAtTop
\AxiomC{$\strut \vdots$}  \noLine
\UnaryInfC{$x \vphantom{y}$}
\AxiomC{$\strut \vdots$}  \noLine
\UnaryInfC{$y$}
\BinaryInfC{$xy$}
\rootAtBottom
\AxiomC{$B$} \noLine
\UnaryInfC{$\strut \vdots$}
\TrinaryInfC{$C$}
\DisplayProof


(2)

\rootAtTop
\AxiomC{$x \vphantom{y}$} \noLine
\UnaryInfC{$\ \vphantom{/}$}
\AxiomC{$y \vphantom{/}$}
\AxiomC{$\ \vphantom{/}$}
\AxiomC{$\ \vphantom{/}$}
\TrinaryInfC{$yz$}
\BinaryInfC{$xyz$}
\rootAtBottom
\AxiomC{}
\BinaryInfC{$xy$}
\AxiomC{$z$}
\BinaryInfC{$C$}
\DisplayProof


Has anyone else encountered proofs like these or have any suggestions?

• Welcome to TeX.SX! Beauty, or awfulness, is perhaps in the eye of the beholder as your pictures look fine to me. I would just use an array or tabular environment, but these would produce diagrams similar to those you already have. Btw, rather than posting code snippets it is much easier for people to you you if you give a full minimal working example. A MWE should start with a \documentclass command, include any necessary packages and be as small as possible to demonstrate your problem. In particular, a MWE should compile.
– user30471
Jun 10 '17 at 4:39

Neither bussproofs nor its more flexible successor ebproof is well-suited to drawing proofs of the kind you need here. Consistency of typesetting is surely a worthy goal, but there are times when a tool just doesn't do what you need.

The proofs would not be hard to do with a tabular or array. Here, I've used a TikZ matrix. Possibly a standard tabular or array would be easier, but the matrix library was in my mind.

Here, first, are the results.

\documentclass[border=10pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{matrix}
\begin{document}
\begin{tikzpicture}
\matrix (e) [matrix of math nodes, nodes in empty cells, nodes={text depth=2.5pt, text height=7.5pt}]
{
A && xy && B\\
\vdots &&&& \vdots\\
\vdots & x && y & \vdots\\
\vdots & \vdots && \vdots & \vdots\\
&& C && \\
};
\draw (e-2-2.center -| e-3-2.west) -- (e-2-4.center -| e-4-4.east) (e-4-1.south -| e-1-1.west) -- (e-4-5.south -| e-1-5.east);
\end{tikzpicture}
\begin{tikzpicture}
\matrix (p) [matrix of math nodes, nodes in empty cells, nodes={text depth=2.5pt, text height=7.5pt}]
{
& xyz & & & \\
& & yz & & \\
x & y & & \\
xy & & & z \\
& & C & & \\
};
\draw (p-1-1.south west) -- (p-1-3.south -| p-2-3.east) (p-2-2.south west) -- (p-2-3.south east) (p-3-1.south -| p-4-1.west) -- (p-3-2.south east) (p-4-1.south west) -- (p-4-4.south east) ;
\end{tikzpicture}
\end{document}