Some commutative diagram commands like the ones in / are available as a separate package, amscd. For complex commutative diagrams authors will need to turn to more comprehensive packages like / (see xypic), but for simple diagrams without diagonal arrows the amscd commands may be more convenient. Here is one example.
\begin{CD}
S^{{\mathcal{W}}_\Lambda}\otimes T @>j>> T\\
@VVV @VV{\End P}V\\
(S\otimes T)/I @= (Z\otimes T)/J
\end{CD}
In the CD environment the commands |@>>>|,
|@<<<|, |@VVV|, and |@AAA| give respectively right, left, down, and up
arrows. For the horizontal arrows, material between the first and second
|>| or |<| symbols will be typeset as a superscript, and material
between the second and third will be typeset as a subscript. Similarly,
material between the first and second or second and third |A|s or |V|s
of vertical arrows will be typeset as left or right ``sidescripts''.