# Forest package: eliminate vertical space between parent and child

I would like to zero the vertical distance between a node and some of their children. (I would be satisfied if I could do this for a node with a single child.) The desired effect is similar to a multiline node using a linebreak, that is, I expected that this

\begin{forest}
[$\alpha$
[$\beta$, l=0mm]
]
\end{forest}


would have an effect similar to this

\begin{forest}
[$\alpha$\\$\beta$, align=center]
\end{forest}


Actually, I was not able to reduce the vertical space reducing the l coordinate, although I could increase the vertical space changing the l coordinate.

The reason I don't use a multiline node is that I would like to use labels to the left of each node.

Why the first code does not have the desired effect and how could I do this?

## 1 Answer

The issue is explained in section 2.4.1 of the manual (and examples immediately preceding it). In short, you must also use l sep=0 on the parent node. The effect is almost the same as with align.

\documentclass{standalone}
\usepackage{forest}
\begin{document}
\begin{forest}
[$\alpha$, l sep=0mm
[$\beta$, l=0mm]
]
\end{forest}
\end{document}

• @SZ: It worked, thanks! – Franc May 15 at 14:19