# TiKZ make lines connecting nodes have the same endpoints

Using the MWE below:

\documentclass{standalone}
\usepackage{tikz}
\usepackage{tikz-qtree}
\usepackage{tikz-qtree-compat}
\usepackage{ textcomp }

\begin{document}
\begin{tikzpicture}
\Tree [
.TP [
.T' \node(C){T+verb}; [
.vP \qroof{ana}.DP [
.v' \node(B){v+{\textlangle}verb{\textrangle}}; [
.VP [
.V' \node(A){V+{\textlangle}verb{\textrangle}}; \qroof{taalib}.DP
]
]
]
]
]
]
\draw [semithick,->] (A) to[out=270,in=180] (B);
\draw [semithick,->] (B) to[out=270,in=180] (C);
\end{tikzpicture}
\end{document}


I get output like this:

The tree would look a lot better and I think be more intuitionally correct if the endpoint of the arrow from "V+" and the starting point of the arrow from "v+" were in the same place, perhaps with a small black dot to connect them. That would better show that the same verb is doing both movements. Does anyone know how to accomplish this?

-
Not sure if I understand correctly but I think you can send the arrows to/from the same point of the node i.e. something like \draw [semithick,->] (A) to[out=270,in=-150] (B.-150);\draw [semithick,->] (B.-150) to[out=-150,in=180] (C); –  percusse Dec 4 '11 at 7:06

You can add a node with a dot and instead of using in and out angles, use the bend parameter.

\documentclass{standalone}
\usepackage{tikz}
\usepackage{tikz-qtree}
\usepackage{tikz-qtree-compat}
\usetikzlibrary{positioning}
\newcommand\TR[1]{\textlangle#1\textrangle}
\usepackage{ textcomp }

\begin{document}
\begin{tikzpicture}
\Tree [
.TP [
.T\1 \node(C){T+verb}; [
.vP \qroof{ana}.DP [
.v\1 \node(B){v+\TR{verb}}; [
.VP [
.V\1 \node(A){V+\TR{verb}}; \qroof{taalib}.DP
]
]
]
]
]
]
\draw [semithick] (A.south) edge [bend left=70,->,shorten >=.2em] (B.south)
node (D) [draw, fill, circle, minimum size=2pt,below = -.25em of B.south,
inner sep=0pt] {} ;
\draw [semithick] (D) edge [bend left=70,->,shorten <=.5em] (C);
\end{tikzpicture}
\end{document}


I also made a couple of other changes (\1 instead of '' for primes, and a command to mark traces, which will save you a lot of typing.

-

You already have a solution with a black dot, but you can also play with start and final anchors. With B.240 syntax you select point on node border at angle 240. Look at the example

\documentclass{standalone}
\usepackage{tikz}
\usepackage{tikz-qtree}
\usepackage{tikz-qtree-compat}
\usepackage{ textcomp }

\begin{document}
\begin{tikzpicture}
\Tree [
.TP [
.T' \node(C){T+verb}; [
.vP \qroof{ana}.DP [
.v' \node(B){v+{\textlangle}verb{\textrangle}}; [
.VP [
.V' \node(A){V+{\textlangle}verb{\textrangle}}; \qroof{taalib}.DP
]
]
]
]
]
]
\draw [semithick,->] (A) to[out=270,in=270] (B.south);
\draw [semithick,->] (B.240) to[out=240,in=180] (C);
\end{tikzpicture}
\end{document}


-
This is great! I'll combine this with Alan Munn's. –  Nate Glenn Dec 5 '11 at 21:09