I am in the middle of writing something exposing various interactions between various properties that have certains objects in some theory in mathematics. I would like to summerize this in a graphe, and I would like it to look like this :

I started to try to do this (without the ellipses...) with the package xypic (that I already use for my diagrams) thanks to the following example stated in the documentation of the package :
\entrymodifiers={++[o][F-]}
\SelectTips{cm}{}
\xymatrix @-1pc
{
*\txt{start} \ar[r]
& 0 \ar@(r,u)[]^b \ar[r]_a
& 1 \ar[r]^b \ar@(r,d)[]_a
& 2 \ar[r]^b
\ar ‘dr_l[l] ‘_ur[l] _(.2)a [l]
&*++[o][F=]{3}
\ar ‘ur^l[lll]‘^dr[lll]^b [lll]
\ar ‘dr_l[ll] ‘_ur[ll] [ll]
}
but I am really not happy with it.
So I wonder if a package devoted to the design of intricate graphs as the one in the graphical example does exist, or at least something apporaching. If not, what would tex-gurus advise in my case ?
I must precise that I would like to avoid using tikz (except if there a dedicated "module" of it answering to my question, but I don't think so) nor any kind of really graphism-oriented latex package if possible, and if the eventual other solution produces diagrams of quality compared to those that tikz would produce.