Why do you think that this is a bug in Allegro?

FWIW it blows up in Cmucl as well, so I suspect that it's a language
issue.

Try the newsgroup comp.lang.lisp.

Larry

feilong wrote:
> 
> Hallo Friends:
> I want to define a strong connected graph with lisp:
> (let ((graph '(a (b nil . nil) c)))
>        (setf (second (second graph)) (second graph))
>       (setf (rest (last (second graph))) (rest (rest graph)))
>        graph)
> but intepreter displays error messages
>  *** - Lisp stack overflow. RESET
> Why is this graph false?
> By the way,how can I correct build a strong-connected graph with lisp
> and how can I such each atom in this graph?
> 
> Best Regurd
> Xu
>