I have seen the following two questions on meta:
http://meta.math.stackexchange.com/questions/3360/xymatrix-commutative-diagrams
http://meta.math.stackexchange.com/questions/2324/how-to-draw-a-commutative-diagram.
Apparently it seems that Math.SE does not support the \begin{xymatrix}
environment. When will this feature come into place? I looked at this answer here on tensor products and the \begin{matrix}
environment looks terribly inadequate. I know of Arturo's fix in the link above, but I think if say we wanted a diagram with diagonal arrows it would be very messy.
Also, if \begin{xymatrix}
comes into Math.SE does that mean that chat will have it to? I have been talking to some people on chat recently and felt that I desperately needed to be able to draw commutative diagrams easily on chat.