# Crossing over method with xy package for one or more arrows

Related on this question, considering the original image,

\documentclass[a4paper,12pt]{article}
\usepackage[all]{xy}
\begin{document}
\xymatrix@R=2pc@C=2.8pc{
& b' \ar@{~>}[ddl]|\hole \ar[dr] & \\
c' \ar@{~>}[d] \ar[ur]  & & \ar@{~>}[ll] a' \ar@{~>}[ddl]|\hole\\
a \ar[rr] \ar[dr]& & c\ar[uul]|\hole \ar[u] \\
& b \ar[ur] \ar[uul]|\hole &
}
\end{document}


I am not able with xy package to hide, through the crossing over method, the same vector as in the initial figure. What is the optimal solution?

• I don't think there's a simple way to do this: xy doesn't "know" what the break is breaking; it simply puts the break at the midpoint of the arrow. You can see this by e.g. changing the arrow between a' and b to be [dl]. The result is a completely misplaced break even though the only arrow crossed is the one between b' and c. Jul 4 at 21:29
• @AlanMunn Hi very kind Alan: Yes it's true. I remember when I had compiled my code a few weeks ago. But whoever had created the first figure what trick did he use? I am not able. :-( Jul 4 at 21:33
• It may be able to be done with the \PATH construct. (But don't ask me how...) :) Jul 4 at 21:50
• @AlanMunn aahahahahah LOL :-)....I have seen something two last weeks for this package but I not remember now nothing. Jul 4 at 21:51