# Create an implication graph in latex

I am trying to create a graph like the one in the image below:

Can someone please help me? I would prefer to do it using tikz if it is possible however any solution would be great.

• Have you looked at for example the second tutorial in the TikZ manual (chapter 3)? While not exactly the same, if you work through that (and possibly the first tutorial), you would probably be able to do most of that yourself, and you can ask when you get stuck. – Torbjørn T. Oct 28 '17 at 16:45
• Thanks, I will look it up and ask if I get stuck. Just to be sure do you mean chapter 3 from this manual texample.net/media/pgf/builds/pgfmanualCVS2012-11-04.pdf? – Razvan Oct 28 '17 at 17:00
• Not exactly, that one's a bit old. Open a terminal/command prompt on your computer and type texdoc tikz, or get it from ctan.org/pkg/pgf – Torbjørn T. Oct 28 '17 at 17:06

Here is a quick start for you, that you can tweak.

The arrow decoration is by Mark Wibrow from here.

\documentclass[border=10]{standalone}
\usepackage{tikz}
\usetikzlibrary{calc,decorations}% for positioning nodes, decorating arrows
\pgfdeclaredecoration{arrows}{draw}{
\state{draw}[width = \pgfdecoratedinputsegmentlength]{%
\path [every arrow subpath/.try] \pgfextra{%
\pgfpathmoveto{\pgfpointdecoratedinputsegmentfirst}%
\pgfpathlineto{\pgfpointdecoratedinputsegmentlast}%
};
}}
\tikzset{% define styles for each node type and edges
base/.style = { circle, draw },
filled/.style = { base, fill = black!50 },
every arrow subpath/.style = { ->, draw, thick }
}
\def\xdist{2}
\def\yheight{2.5*\xdist}
\begin{document}
\begin{tikzpicture}
% draw all the nodes first
\draw node[filled] (1)                                     {1}
node[filled] (3) at ($(1)-(0,\yheight)$)             {3}
node[filled] (2) at ($(1)!.5!(3)$)                   {2}
node[base]   (9) at ($(2)+(-4*\xdist,0)$)            {9}
node[base]   (7) at ($(9)+(\xdist,-0.6*\xdist)$)     {7}
node[base]   (8) at ($(9)+(2*\xdist,0)$)             {8}
node[base]   (4) at ($(8)!.5!(1)$)                   {4}
node[base]   (6) at ($(4)-(2*\xdist,0)$)             {6}
node[base]   (5) at ($(8)!.5!(3)$)                   {5}
;
% now the fun with arrows
\draw[decoration=arrows, decorate]
(9) -- (8) -- (4) -- (1)
(6) -- (8) -- (5) -- (3)
(7) -- (8) -- (4) -- (1)
(4) -- (2)
(5) -- (2)
;
\end{tikzpicture}
\end{document}


• This is a fantastic answer! thank you very much :) – Razvan Nov 1 '17 at 11:27