[Xy-pic] axis with ticks

[Pol]

Ross Moore wrote:
> 
> If you cannot access these directly, then become a member of TUG.
> That will grant you access to all TUGboat articles online.
> 

Thank you, but it takes too time learning those new instructions. Also, i
doubt they cannot be rendered by the lyx editor.
Luckly I have found a simpler solution, having recourse to frame decorations
to add labels:
  
\xymatrix{ &  & Y\\
 &  & 2\,- &  &  & \\
 &  & 1\,- & \\
\ar@{-}[rr] & \overset{|}{\overset{}{-1}\,\,\,\,} & O\ar@{>}[uuu]\ar@{>
[rrrr] & \overset{|}{\overset{}{1}} & \overset{|}{\overset{}{2}} &
\overset{|}{\overset{}{3}} & X\\
 &  & -1\,-\,\,\,\,\,\\
 &  & \ar@{-}[uu]}


---Paolo