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

Question

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!

Answer 1

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}