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?

[description,inner sep=0mm,fill=none]and adjust if it works as you wish. – percusse Apr 06 '12 at 22:10inner sep=-3mmis not a good idea since you would be defining a node which has a -3mm long padding and that might cause trouble. Onlyfill=nonewould remove the space effect since right now it's painting white to act as if there is actually a space there. Change it tofill=yellowand you would see what I mean. – percusse Apr 06 '12 at 22:32doubleline. – percusse May 23 '13 at 09:40