# A scheme in LaTeX

I have 5 statements and some of them are equivalent, for some of them implications hold only in one direction. I would like to draw the scheme of these relations in LaTeX. Fortunately, two pairs of these statements are equivalent, so the scheme will not be overloaded with arrows.

In fact, there will be a triangle with 3 nodes (1),(2),(3) with some arrows between them, and (4) will have just a connection with (2), (5) will have the only connection with (3).

How to draw it in LaTeX? Here is an example from Visio: however I need arrows to be without corners and like $\Rightarrow$ or $\Leftrightarrow$.

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I think a link to a graphical example would be useful here. –  Joseph Wright Jul 4 '11 at 8:46
@Joseph: Could I upload it here, or I should use an external website? If I could do it here, please tell me how. –  Ilya Jul 4 '11 at 8:48
As new user without image posting privileges simply include the image as normal and remove the ! in front of it to turn it into a link. A moderator or another user with edit privileges can then reinsert the ! to turn it into an image again. (There is an 'Add image' button in the question editor.) –  Joseph Wright Jul 4 '11 at 8:55
@Joseph: thanks, I've done. –  Ilya Jul 4 '11 at 9:05
Do you need that rectangular arrangement of the arrows between 4 and 2, and 3 and 5, or should that just be a straight line without corners? –  Brent.Longborough Jul 4 '11 at 9:37

This is the closest to $\Rightarrow$ I found. I was too lazy, so it's with absolute positioning ;)

EDIT: Should have read the question. Now with only one connection between 2/4 and 3/5

\documentclass[12pt]{article}
\usepackage{tikz}
\usetikzlibrary{arrows}
\begin{document}
\begin{figure}
\begin{center}
\begin{tikzpicture}
\node[draw,circle] (s1) at (0,0) {1};
\node[draw,circle] (s2) at (-1.6,-2) {2};
\node[draw,circle] (s3) at (1.6,-2) {3};
\node[draw,circle] (s4) at (-4,-3) {4};
\node[draw,circle] (s5) at (4,-3) {5};
\path
(s2) edge[->, double distance=1pt, >=latex', bend left=40] (s1)
(s3) edge[->, double distance=1pt, >=latex', bend right=40] (s1)
(s3) edge[->, double distance=1pt, >=latex', bend left=60] (s2)
(s2) edge[<->, double distance=1pt, >=latex'] (s4)
(s3) edge[<->, double distance=1pt, >=latex'] (s5);
\end{tikzpicture}
\end{center}
\caption{Five strange statements.}
\label{fig1}
\end{figure}
\end{document}

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surprisingly works now, strange that it does not work before. –  Ilya Jul 6 '11 at 13:31

OK, I'm not sure I fully understand the question, but here's a possible answer using TikZ...

Edited: I'm not very experienced with figures; here's something "that appears to work", and incorporates @Nikolaus Mayer's (+1) arrows. Note that figures are floats, so your figure, rather than disappearing, may have just moved to a less convenient point in your document...

\documentclass[12pt]{article}
\usepackage{tikz}
\usetikzlibrary{arrows}
\begin{document}
\begin{figure}
\begin{center}
\begin{tikzpicture}[>=latex,every node/.style={draw,circle,minimum width={3em},node distance=6em}]
\node (a) {1};
\node [below left of=a] (b) {2};
\node [below left of=b] (d) {4};
\node [below right of=a] (c) {3};
\node [below right of=c] (e) {5};
\draw [->] (b) -- (a);
\draw [->] (c) -- (a);
\draw [->] (c) -- (b);
\draw [<->] (b) -- (d);
\draw [<->] (c) -- (e);
\end{tikzpicture}
\caption{This is a figure}
\end{center}
\end{figure}
\end{document}

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Thank you, it's almost perfect. Is it possible to make arrows of the desired style like $\Rightarrow$? –  Ilya Jul 4 '11 at 10:03
also, how can I label this picture and write a capture for it? If I use figure environment, the picture vanishes. –  Ilya Jul 4 '11 at 10:17