Re: [sage-devel] Nauty as a default generator for graphs

[Nicolas M. Thiery]

On Fri, Mar 09, 2018 at 08:19:19AM +0200, Jori Mäntysalo wrote:
> It is much faster to say sum(1 for _ in graphs.nauty_geng(7)) than sum(1 for
> _ in graphs(7)), and after #19919 we have nauty as a standard package.
> 
> Will I break something if I change graphs(n) without any additional
> parameter to use nauty? A user really needing the old code could then say
> graphs(n, property=lambda x: True). I think that Sage documentation makes no
> promise at all about the order in which graphs are generated.

I am all for it. Nauty is sooo much faster. In fact, I'd be glad if
some of Nauty's arguments would be exposed, in particular to generate
acyclic graphs, ...

Cheers,
Nicolas

PS: +1 as well to Graphs(10), in particular to provide an easy access
point for computing the number of graphs using Pólya enumeration. Yes,
we need to settle for a definition of containment, but that should not
be too hard.

--
Nicolas M. Thiéry "Isil" 
http://Nicolas.Thiery.name/

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Re: [sage-devel] Nauty as a default generator for graphs

[Jori Mäntysalo]

On Fri, 9 Mar 2018, David Roe wrote:


Will I break something if I change graphs(n) without any
additional parameter to use nauty?


It did the change at https://trac.sagemath.org/ticket/24951


Sounds good to me.  You might add an algorithm keyword to the graphs
function, which defaults to nauty.


Not sure... It can be done with property=lambda _: True. I think that 
mostly algorithm-keyword should have a meaning -- there should be a 
situation where someone would prefer one over the other.


On Fri, 9 Mar 2018, 'Martin R' via sage-devel wrote:

Besides, it would also be supercool to have a class Graphs analogous to 
the class Posets, and have the cardinality of the first few layers built 
in (analogous to Posets(16).cardinality())


I am not sure about that. What should be the meaning of, say "g in 
graphs(10)" or "g in graphs"?


--
Jori Mäntysalo

Re: [sage-devel] Nauty as a default generator for graphs

[David Roe]

On Fri, Mar 9, 2018 at 1:19 AM, Jori Mäntysalo 
wrote:

> It is much faster to say sum(1 for _ in graphs.nauty_geng(7)) than sum(1
> for _ in graphs(7)), and after #19919 we have nauty as a standard package.
>
> Will I break something if I change graphs(n) without any additional
> parameter to use nauty? A user really needing the old code could then say
> graphs(n, property=lambda x: True). I think that Sage documentation makes
> no promise at all about the order in which graphs are generated.


Sounds good to me.  You might add an algorithm keyword to the graphs
function, which defaults to nauty.
David


>
>
> --
> Jori Mäntysalo
>

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[sage-devel] Nauty as a default generator for graphs

[Jori Mäntysalo]

It is much faster to say sum(1 for _ in graphs.nauty_geng(7)) than sum(1 
for _ in graphs(7)), and after #19919 we have nauty as a standard package.


Will I break something if I change graphs(n) without any additional 
parameter to use nauty? A user really needing the old code could then say
graphs(n, property=lambda x: True). I think that Sage documentation makes 
no promise at all about the order in which graphs are generated.


--
Jori Mäntysalo