# How can I write 3-dimensional diagrams in XYmatrix with parallel arrows?

I'm trying to fix the following diagram that I wrote in XYmatrix. I want to make it a cube or at least a parallelogram, but I don't know how to deal with the different lenghts of the names of the objects.. This is my code:

\xymatrix{
& Ker(\pi_\phi\flat(\pi_\phi\flat\pi_\psi)) \ar@{ >->}[rr] \ar[dl]_-{\overline{k_{(\cdots),(\cdots)\flat(\cdots)}}\ \ \ \ \ \ } \ar'[d]^{\overline{\mu_{(\cdots)}^{(\cdots)}}}[dd]
& & ((X,\phi)\rtimes A)\flat(((X,\phi)\rtimes A)\flat ((Y,\psi)\rtimes B)) \ar[dd]^-{\mu_{(\cdots)}^{(\cdots)}} \ar[dl]_-{k_{(\cdots),(\cdots)\flat(\cdots)}\ }
\\
Ker(\pi_\phi+(\pi_\phi\flat\pi_\psi)) \ar@{ >->}[rr] \ar[dd]_-{\overline{\binom{i_{(X,\phi)\rtimes A}}{k_{(\cdots),(\cdots)}}}}
& & ((X,\phi)\rtimes A)+(((X,\phi)\rtimes A)\flat ((Y,\psi)\rtimes B)) \ar[dd]^<<<<<<<<{\binom{i_{(X,\phi)\rtimes A}}{k_{(\cdots),(\cdots)}}}
\\
& Ker(\pi_\phi\flat\pi_\psi) \ar@{ >->}'[r][rr] \ar[dl]_-{\overline{k_{(\cdots),(\cdots)}}\ \ \ \ }
& & ((X,\phi)\rtimes A)\flat((Y,\psi)\rtimes B) \ar@{ >->}[dl]^-{k_{(\cdots),(\cdots)}}
\\
Ker(\pi_\phi+\pi_\psi) \ar@{ >->}[rr] & & ((X,\phi)\rtimes A)+((Y,\psi)\rtimes B)
}


Any help would be appreciated!

• Maybe you could consider using tikzcd. The alignment could be easier. Or, try to change distance between cols using \xymatrix@C=0.5cm{...} and add or delete more cols. Feb 2, 2018 at 14:48
• I agree with you that the best solution would be to use tikzcd, but I wrote many diagrams in xymatrix so far, and it would take too much effort/time to shift from one environment to the other (I don't like to mix stuff.. my bad). So I'm wondering if there is an easier solution (in xymatrix) to my problem. Moreover I dont think that adding columns or widening all the columns at the same time can solve the issue since it arises from the fact that some columns are larger than others due to the different lenghts of the objects Feb 2, 2018 at 15:09
• I got problem to compile your code (Xy-pic error: illegal <dir>: \dir { >} not defined. }). Please, post a MWE with packages. Feb 2, 2018 at 15:16
• I found problem, the space in { >->}. Feb 2, 2018 at 15:19
• See Answer to exercise 19 from XY-pic User’s Guide. It could help since there you find entries with different sizes. Feb 2, 2018 at 15:36

I suggest to switch to tikz-cd:

\documentclass{article}
\usepackage[a4paper,landscape]{geometry}
\usepackage{amsmath,amssymb}
\usepackage{tikz-cd}

\newcommand{\bflat}{\mathbin{\flat}}
\DeclareMathOperator{\Ker}{Ker}

\begin{document}

\begin{tikzcd}[column sep={12em,between origins},row sep=4em]
&
\Ker(\pi_\phi\bflat(\pi_\phi\bflat\pi_\psi))
\arrow[rr,rightarrowtail]
\arrow[dl,swap,"\overline{k_{(\cdots),(\cdots)\bflat(\cdots)}}"]
\arrow[dd,swap,"\overline{\mu_{(\cdots)}^{(\cdots)}}" near start]
&&
((X,\phi)\rtimes A)\bflat(((X,\phi)\rtimes A)\bflat ((Y,\psi)\rtimes B))
\arrow[dd,"\mu_{(\cdots)}^{(\cdots)}"]
\arrow[dl,swap,"k_{(\cdots),(\cdots)\bflat(\cdots)}"]
\\
\Ker(\pi_\phi+(\pi_\phi\bflat\pi_\psi))
\arrow[rr,rightarrowtail,crossing over]
\arrow[dd,swap,"\overline{\binom{i_{(X,\phi)\rtimes A}}{k_{(\cdots),(\cdots)}}}"]
&&
((X,\phi)\rtimes A)+(((X,\phi)\rtimes A)\bflat ((Y,\psi)\rtimes B))
\\
&
\Ker(\pi_\phi\bflat\pi_\psi)
\arrow[rr,rightarrowtail]
\arrow[dl,swap,"\overline{k_{(\cdots),(\cdots)}}"]
&&
((X,\phi)\rtimes A)\bflat((Y,\psi)\rtimes B)
\arrow[dl,rightarrowtail,"k_{(\cdots),(\cdots)}"]
\\
\Ker(\pi_\phi+\pi_\psi)
\arrow[rr,rightarrowtail]
&&
((X,\phi)\rtimes A)+((Y,\psi)\rtimes B)
\arrow[uu,leftarrow,crossing over,swap,"\binom{i_{(X,\phi)\rtimes A}}{k_{(\cdots),(\cdots)}}" near end]
\end{tikzcd}

\end{document}