[Nauty-list] status of generator for undirected multigraphs?

[Michael Kiermaier]

> [...]
> That's it.  Note that x=0 and y=0 are forbidden.  This rule can
> be relaxed slightly, but care is needed.  It is important that for any
> vertex z[0,j], the vertices z[1,j],...,z[k-1,j] are combinatorially
> determined, which is not always true if x=0 and y=0 are allowed without
> restriction.

Thanks for the explanation, I think I got it.

To make this method work, it is necessary that for all j and all 1<=i<=k
there is an edge (z[0,j],z[i,j]).
Thats the reason why the "path" layer-connection type does not work any
more and why "star" has its center in layer 0, right?

~michael