On Mon, Jan 12, 2015 at 10:08 AM, William Stein <wst...@gmail.com> wrote:
>
>
> On Mon, Jan 12, 2015 at 8:58 AM, Nathann Cohen <nathann.co...@gmail.com>
> wrote:
>>
>> > The best outcome would be to have a true "how do I do *** in Sage"
>> > document
>> > that keeps being updated;
>>
>> A small remark: in combinatorial designs and graphs the anser to "How
>> do I build ***" is rather well answered by graphs.<tab>,
>> digraphs.<tab>, designs.<tab>. It gives a nice entry point for the
>> functions that "build something", and from there the classes/functions
>> doc is sufficient in our case.
>>
>> Of course I have no idea how that applies for other fields. But I
>> would not be surprised if we could simply remove the groups/codes
>> entries of the construction manual, after checking that all that it
>> says can already be found through the groups.<tab> and codes.<tab>
>> objects.
>>
>
> You are assuming that the only target audience of the constructions guide is
> a person actively using an interactive Sage session, but that is not the
> only target audience. Google searches, especially from people who might
> have never heard of Sage, are a big target audience for the constructions
> guide.
>
> I definitely would encourage you to do the above though and make sure
> blah.<tab> is as good as possible.
>
> By the way, yesterday at the Sage booth at the Joint Math meetings somebody
> walked up and said, "can you use Sage to enumerate the groups of order 16?"
> For a group theorist, this is a very natural basic question. I tried
> groups.[tab] and found nothing useful. I tried searching the sage reference
> manual and couldn't figure it out. I then of course googled for GAP and
> that sort of question, and found how to do it directly with GAP and did.
> However, I could not figure out how to convert a gap group back to Sage.
Depends on the group:
sage: G = gap("DihedralGroup(4)")
sage: G.sage()
---------------------------------------------------------------------------
...
NotImplementedError: Unable to parse output: Group( [ f1, f2 ] )
sage: G = gap("SymmetricGroup(4)")
sage: G.sage()
Symmetric group of order 4! as a permutation group
> And I couldn't figure out how to list the elements of a GAP group. So I'm
I didn't know either but after G.<tab> I looked for a command involving either
List or Element and found AsSortedList:
sage: G = gap("DihedralGroup(4)")
sage: G.AsSortedList()
[ <identity> of ..., f1, f2, f1*f2 ]
> definitely not so happy with the group theory functionality in Sage, or at
> least its documentation.
I don't know about David Kohel but it would not bother me if our paper
"Group theory in Sage"
http://boxen.math.washington.edu/home/wdj/expository/groups-sage4.pdf
was included in the Sage documentation.
> Remember, this was all in front of an impatient *potential* Sage users, so I
> don't get 20 minutes to try to figure out each thing -- if I can't in 1
> minute, we lose.
>
> I don't even know if there any group theorists at all that use Sage...
>
I'm guessing most group theorists deal with infinite groups or modular
representation theory (or both) and Sage does not implement those
via GAP.
> Anyway, an ideal entry in the constructions guide would be "How do I
> construct a list of all groups of order 16?"
>
The simplest explanation would be to use the small groups database
which can be installed into Sage, but it is not open-source licensed.
> -- William
>
>
>
>
>
>
>
>
>>
>> Nathann
>>
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>
>
>
>
> --
> William Stein
> Professor of Mathematics
> University of Washington
> http://wstein.org
>
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