Wavy arrows in xy-pic

Question

What method should I use, to draw beautiful wavy arrows.

So far I tried the following. I use xy-pic package, there I use @{~>} definition for the arrow.

The code I've composed is like this:

\begin{figure}
\centering
\mbox{
\xygraph{
!{<0cm,0cm>;<1cm,0cm>:<0cm,1cm>::}
!{(0,0) }*+{\bullet_{x}}="x"
!{(2,0) }*+{\bullet_{v''}}="v"
!{(4,0) }*+{\bullet_{y}}="y"
!{(2,1) }*+{\bullet_{u}}="u"
!{(2,-2) }*+{\bullet_{z}}="z"
"x":@{~>}"v"
"v":@{~>}"y"
"y":@/_/@{~>}"u"
"u":"v"
"v":@{~>}"z"
}}
\end{figure}

And the result is like this:

The problems that I see in this drawing are:

• In the arrows from x to v'' and from v'' to y the composition of last "~" and the ending ">" is not good.
• The arrow from v'' to z is cutted after each "~"
• The arrow from y to u looks awful.

I search for a tip how to improve the quality of the figure. Thanks.