[Tex/LaTex] How to prevent a TikZ arrow from touching a node

arrowsnodestikz-pgf

I am using TikZ to draw some trees in my thesis. This is a sample of what is being done:

\documentclass{article}
\usepackage{tikz-qtree}

\newcommand{\Ta}{
\begin{tikzpicture}[level distance=30pt, sibling distance=90pt]
  \node {}
        child {node {$p(x)$}
        child{node {$skipped$} edge from parent[draw=none]}
    }
        child {node {$s(x)$}
        child {node {$\sim s(x)$}
            child{node {$closed$} edge from parent[draw=none]}
        }   
    };
\end{tikzpicture}
}

\newcommand{\Tb}{
\begin{tikzpicture}[level distance=30pt, sibling distance=90pt]
\tikzstyle{level 2}=[level distance=30pt, sibling distance=80pt]
  \node {}
        child {node {$p(x)$}
        child{node {$q(x)$}
            child{node {$skipped$} edge from parent[draw=none]}
        }
        child{node {$\sim p(x)$}
            child{node {$closed$} edge from parent[draw=none]}
        }
    }
        child {node {$s(x)$}
        child {node {$\sim s(x)$}
            child{node {$closed$} edge from parent[draw=none]}} 
    };
\end{tikzpicture}
}


\newcommand{\Tc}{
\begin{tikzpicture}[level distance=30pt, sibling distance=90pt]
\tikzstyle{level 1}=[sibling distance=90pt]
\tikzstyle{level 2}=[sibling distance=80pt]
\tikzstyle{level 3}=[sibling distance=40pt]
  \node {}
        child {node (n1) {$p(x)$}
        child{node {$q(x)$}
            child{node (n2) {$\sim p(x)$}
                child{node {$closed$} edge from parent[draw=none]}
            }
            child{node {$\sim q(x)$}
                child{node {$closed$} edge from parent[draw=none]}
            }
            child{node {$ r(x)$}
                child{node {$skipped$} edge from parent[draw=none]}
            }
        }
        child{node {$\sim p(x)$}
            child{node {$closed$} edge from parent[draw=none]}
        }
    }
        child {node {$s(x)$}
        child {node {$\sim s(x)$}
            child{node {$closed$} edge from parent[draw=none]}} 
    };

\path[dashed, <->](n1)edge [bend right=45]  node[above left]{reduction}(n2);

\end{tikzpicture}
}

\begin{document}
\pgfversion

\begin{figure}
\centering
\begin{minipage}{0.45\textwidth}
\centering\Ta
\caption{$Ta$}
\end{minipage}
\begin{minipage}{0.45\textwidth}
\centering\Tb
\caption{$Tb$}
\end{minipage}
\vspace{15pt}
\vspace{15pt}
\begin{minipage}{0.45\textwidth}
\centering\Tc
\caption{$Tc$}
\end{minipage}
\end{figure}


\end{document}

There is one little problem I cannot solve. The command:

\path[dashed,<->](n1)edge [bend right=45]  node[above left]{reduction}(n2);

produces a line that is touching the bottom node, and this is a little annoying.

enter image description here

I tried different approaches but nothing seemed to work. Can anyone help me figure this out?

Best Answer

The problem is caused by the tikz-qtree package. If you aren't using its methods for inputting trees, you shouldn't load it. (Another reason to make a minimal working example.)

However, because of the way tikz-qtree draws its trees, you might prefer the tree to look that way, in which case Martin's solution will solve the problem. Here's a comparison of the same tree with tikz-qtree loaded and not loaded: (The one with tikz-qtree uses the shorten solution on the path.)

Without tikz-qtree

tree without tikz-qtree loaded

With tikz-qtree

tree with tikz-qtree loaded

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