[Nauty] New release of nauty: 2.2b5
Brendan McKay
bdm at cs.anu.edu.au
Sun May 11 00:41:01 EST 2003
* Sterten at aol.com <Sterten at aol.com> [030511 00:02]:
> Brendan wrote:
>
> >nauty22b5.tar.gz, available at http://cs.anu.edu.au/~bdm/nauty,
>
> I like this directg.
> To build it with GCC and all my old .o files from the
> last version still present, I had to copy the new naugroup.c,directg.c
That's ok in this case, but in general I can't guarantee correctness if
you use a mixture of old and new files.
> >Read undirected graphs and orient their edges in all possible ways.
> >Edges can be oriented in either or both directions.
>
> you mean:
> all 4 possibilities between 2 different vertices are included,
> so all irreflexive relations or binary adjacency matrices with 0 in the
> main diagonal are allowed.
No, only three possibilities: x->y, x<-y, x<->y
> For a possible further restriction we can use the -o switch.
In which cases there are two possibilities: x<-y, x->y
> > -e#:# specify a value or range of the number of directed edges
>
> total number of edges, not edges between two vertices
Right, I changed the wording.
> > -o orient each egde in only one direction, never both
>
> 0 or 1 directed edge between two vertices
No, exactly one directed edge.
> > -T use a simple text output format (nv ne edges) instead of digraph6
>
> I'd like the adjacency matrix as additional option (just 0s and 1s)
> in one line with an optional blank when the source-vertex changes
The eventual plan is to have a standard digraph format that can be
recognised and converted to many other forms by listg and showg.
> >Tournaments of order 7:
> >% geng -cq 7 21 | directg -u -o
> >>Z 1 graphs read from stdin; 456 digraphs generated; 3.10 sec
> >(This is the worst case for the program and is certainly NOT a good way to
> >generate tournaments. If you want some small tournaments you are better
> >off fetching them from http://cs.anu.edu.au/~bdm/data/digraphs.html.)
>
> "good" means "fast" here ?
Yes.
> But it's still useful to have this directg.exe method at hand.
>
> >There is currently no method provided for generating strongly-connected
> >digraphs, but I'm thinking about it. Nor is there a way to include loops.
>
> ...yet ? or never will be ?
Depends on demand and time. Similarly multiple edges. Both can be
implemented using much the same method.
Brendan.
More information about the Nauty
mailing list