What is the TeX code for a vertical \mapsto
symbol? I've looked but can't find it.
I'm drawing a commutative diagram, and I want to draw what a specific symbol is being mapped to as well, so I am doing this on the label of the vertical arrow, by adjusting the position of the elements of the label. The rest has worked fine, all I need is a vertical \mapsto
symbol. The best I can do at the moment is to use \downarrow
and put a hyphen slightly above, but that doesn't look great.
\usepackage[all]{xy}
\xymatrix{
0 \ar[r] &
A_{n+1} \ar[r] \ar[d] &
B_{n+1} \ar[r] \ar[d] &
C_{n+1} \ar[r] \ar[d] &
0 \ar[d]
\\
&
A_n \ar[r] \ar[d] &
B_n \ar[r] \ar[d]^(0.25){b}^(0.6){d_{n}} &
C_n \ar[r]^{g_n} \ar[d]_(0.3){c}_(0.44){ \; \; - }_{ \downarrow}_(0.7){0} &
0 \ar[d]
\\
&
A_{n-1} \ar[r]^(0.2){a} &
B_{n-1} \ar[r]^{f_{n-1}} &
C_{n-1} \ar[r] & 0
}