15

I'm using TikZ for the first time to draw a simple Kripke model, and I'm using the child notation to produce new nodes. How can I turn my edges into arrows?

\begin{tikzpicture}
  \node [circle,draw] (q0) {}
  child {node [circle,draw] (q1) {$p$}
    child {node [circle,draw] (q4) {$p$}
      child {node [circle,draw] (q7) {$p\land q$}}
      child {node [circle,draw] (q8) {$p\land q$}}
      child {node (q9) {} edge from parent[->, dashed]}}
    child {node [circle,draw] (q5) {$q$}}
    child {node (q6) {} edge from parent[dashed]}}
  child {node [circle,draw] (q2) {$p$}}
  child {node (q3) {} edge from parent[dashed]};
\end{tikzpicture}

I know how to change the color or thickness of all edges by passing an option at the beginning of \begin{tikzpicture}, but I can't turn them into arrows.

Also, while we're at it, is there a way to label these edges? Or am I left with simply using node notation for all my nodes?

Thanks for all your help,
Piotr

pkazmierczak
  • 457

1 Answers1

17

You can use edge from parent/.style to use arrows; using edge from parent you can label the edges:

\documentclass[12pt,a4paper]{article}
\usepackage{tikz}
\usetikzlibrary{trees,arrows}
\begin{document}

\begin{tikzpicture}[edge from parent/.style={draw,-latex}]
  \node [circle,draw] (q0) {}
  child {node [circle,draw] (q1) {$p$}
    child {node [circle,draw] (q4) {$p$}
      child {node [circle,draw] (q7) {$p\land q$} edge from parent node[left,near start] {a}}
      child {node [circle,draw] (q8) {$p\land q$}}
      child {node (q9) {} edge from parent[->, dashed]}}
    child {node [circle,draw] (q5) {$q$}}
    child {node (q6) {} edge from parent[dashed]}}
  child {node [circle,draw] (q2) {$p$}}
  child {node (q3) {} edge from parent[dashed]};
\end{tikzpicture}
\end{document}

enter image description here

Gonzalo Medina
  • 505,128