# not implies, not Leftarrow, description in the middle of an arrow in TikZ-cd

Is there a way to put $\nLeftarrow$ instead of some arrows in TikZ? Specifically, how do I change it to "B does not imply A" in the following code.

\documentclass{article}
\usepackage{tikz-cd}
\begin{document}
\begin{tikzcd}[arrows=Rightarrow]
A \arrow[out=30,in=150]{r}{}\arrow{d} & B \arrow[out=210,in=330]{l}{}\arrow{d}  \\
E  \arrow{r}{} & F
\end{tikzcd}
\end{document}


One very primite way is to do something similar to the following, where at the description part in the middle of the arrow, use \Big\backslash.

\documentclass{article}
\usepackage{tikz-cd}
\begin{document}
\begin{tikzpicture}
\matrix (m) [matrix of math nodes, row sep=3em, column sep=3em]
{ A & B \\
& C \\ }; \path[->,font=\scriptsize] (m-1-1) edge node
{$\Big\backslash$} (m-1-2) edge node {$\Big\backslash$} (m-2-2);
\end{tikzpicture}
\end{document}


But then, how do I put a description in the middle of an arrow in the first code?

-

This is probably the same mechanism for description key in the manual of tikz-cd but more explicit.

\documentclass{article}
\usepackage{tikz-cd}
\usetikzlibrary{decorations.markings}
\tikzset{degil/.style={
decoration={markings,
mark= at position 0.5 with {
\node[transform shape] (tempnode) {$\backslash$};
%\draw[thick] (tempnode.north east) -- (tempnode.south west);
}
},
postaction={decorate}
}
}
\begin{document}
\begin{tikzcd}[arrows=Rightarrow]
A \arrow[out=30,in=150,degil]{r}{}\arrow[degil]{d} & B \arrow[out=210,in=330]{l}{}\arrow{d}  \\
E  \arrow{r}{} & F
\end{tikzcd}
\end{document}


If you want to keep the backslashes upright(unrotated) regardless of the arrow direction, you can remove the transform shape option and give it a try.

-
Description works as well,but leaves some space in between. Your way was better,thank you. –  Derya Apr 6 '12 at 21:51
@Derya Try also [description,inner sep=0mm,fill=none] and adjust if it works as you wish. –  percusse Apr 6 '12 at 22:10
Both [description,inner sep=0mm,fill=none] and [description,inner sep=-3mm] works. –  Derya Apr 6 '12 at 22:19
@Derya Sorry for the follow-up but inner sep=-3mm is not a good idea since you would be defining a node which has a -3mm long padding and that might cause trouble. Only fill=none would remove the space effect since right now it's painting white to act as if there is actually a space there. Change it to fill=yellow and you would see what I mean. –  percusse Apr 6 '12 at 22:32
Opps, you are right, thanks again. –  Derya Apr 6 '12 at 22:55