Opened 4 years ago

Closed 4 years ago

#18774 closed enhancement (fixed)

Janko Groups and Livingstone graph

Reported by: ncohen Owned by:
Priority: major Milestone: sage-6.8
Component: group theory Keywords:
Cc: dimpase, vdelecroix Merged in:
Authors: Nathann Cohen Reviewers: Dima Pasechnik
Report Upstream: N/A Work issues:
Branch: d07e879 (Commits) Commit: d07e879d167c82d8f304b055ee290c67e57374e0
Dependencies: Stopgaps:

Description

This branch exposes the Janko groups from gap, and builds the Livingstone Graph from J1

https://en.wikipedia.org/wiki/Janko_group https://en.wikipedia.org/wiki/Livingstone_graph

Nathann

Change History (28)

comment:1 Changed 4 years ago by ncohen

  • Branch set to public/18774
  • Cc vdelecroix added
  • Commit set to 42e61b8290df7dd67a5a0e14c6f9101750f249bc
  • Status changed from new to needs_review

New commits:

42e61b8trac #18774: Livingstone Graph and Janko Groups

comment:2 Changed 4 years ago by git

  • Commit changed from 42e61b8290df7dd67a5a0e14c6f9101750f249bc to 8b7160a453bbd24d5e684f9577115ad963188ef6

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

8b7160atrac #18774: Livingstone Graph and Janko Groups

comment:3 follow-up: Changed 4 years ago by dimpase

  • Status changed from needs_review to needs_work

JankoGroup(4) should throw NotImplementedError; I don't think anyone wants a permutation group of degree 173067389, and they aren't known by AtlasRep, as far as I know (IMHO they have the same data as in http://brauer.maths.qmul.ac.uk/Atlas/v3/spor/J4/).

gap> i:=AtlasGroup("J4");
<matrix group of size 86775571046077562880 with 2 generators>

while for the remaining values of k<4 you get

gap> i:=AtlasGroup("Jk");
<permutation group of size ....... with 2 generators>
Last edited 4 years ago by dimpase (previous) (diff)

comment:4 Changed 4 years ago by git

  • Commit changed from 8b7160a453bbd24d5e684f9577115ad963188ef6 to 7efe54b39c46a81ce862fc5e395db3a456127b43

Branch pushed to git repo; I updated commit sha1. New commits:

7efe54btrac #18774: no J4

comment:5 in reply to: ↑ 3 Changed 4 years ago by ncohen

  • Status changed from needs_work to needs_review

Hello,

JankoGroup(4) should throw NotImplementedError;

Right, right. I simplified it and requested an integer from 1 to 3 instead.

Nathann

comment:6 follow-up: Changed 4 years ago by chapoton

  • Status changed from needs_review to needs_work

tests do not pass

shouldn't this be tagged optional - gap_something ?

comment:7 in reply to: ↑ 6 Changed 4 years ago by ncohen

shouldn't this be tagged optional - gap_something ?

HMmm... Gap isn't optional. And with gap installed on my computer, I did not notice that an optional package was needed ^^;

I don't even know which package is needed O_o

Nathann

comment:8 follow-up: Changed 4 years ago by dimpase

you need internet access to use AtlasRep? in GAP. I also think that AtlasRep? comes in gap_packages, i.e. is optional.

(I'm currently travelling, so please excuse my non-constant attention)

comment:9 in reply to: ↑ 8 Changed 4 years ago by ncohen

Hellooooo !

you need internet access to use AtlasRep? in GAP.

Whaaaaaaaaat ? I'll check this immediately.

I also think that AtlasRep? comes in gap_packages, i.e. is optional.

Yep. It is inside.

Nathann

comment:10 Changed 4 years ago by git

  • Commit changed from 7efe54b39c46a81ce862fc5e395db3a456127b43 to 93801c8bd1834243c34eed3bc78b0113c26439b1

Branch pushed to git repo; I updated commit sha1. New commits:

93801c8trac #18774: optional gap packages

comment:11 follow-up: Changed 4 years ago by ncohen

  • Status changed from needs_work to needs_review

It works offline, but gap_packages must be installed.

comment:12 in reply to: ↑ 11 ; follow-up: Changed 4 years ago by dimpase

Replying to ncohen:

It works offline,

Really? http://www.math.rwth-aachen.de/~Thomas.Breuer/atlasrep/ (the official www-pages of the package) says

 Note that the package archives do NOT contain the database part of the package; the GAP interface accesses the data on demand via the internet.

comment:13 in reply to: ↑ 12 ; follow-up: Changed 4 years ago by ncohen

Really?

I built if offline. You think that they have a caching mechanism for that, between sessions?...

Nathann

comment:14 in reply to: ↑ 13 Changed 4 years ago by dimpase

Replying to ncohen:

Really?

I built if offline. You think that they have a caching mechanism for that, between sessions?...

of course you can build it offline, but not use offline (although perhaps some of its data is in other GAP databases).

perhaps one has to read its code...

Nathann

comment:15 Changed 4 years ago by dimpase

TFM says:

4.3 User Parameters for the AtlasRep Package

This section lists global parameters for which it might make sense to change their defaults by assignments to global variables, either just for the current GAP session or as user preferences in the user's gaprc file (see Reference: The gap.ini and gaprc files). For an overview of these parameters, see AtlasOfGroupRepresentationsUserParameters (4.3-8).

4.3-1 Local or Remote Access

There are two possibilities to use the AtlasRep package.

Local access only (offline)

    You can restrict the access to the data that are actually stored in the local installation of GAP.
Remote access (online)

    If your computer is connected to a network that provides access to the ATLAS data (for example the internet) then the functions of the package may fetch the requested data automatically from remote servers when they are required for the first time; these data are then by default stored in the local copy, so later access to them needs no network transfer.

The latter possibility is presently not used by other GAP packages, so it may be regarded as an important feature of the AtlasRep package. Anyhow it requires a few words of explanation.
...

comment:16 follow-up: Changed 4 years ago by ncohen

I just did the following:

  • Went offline
  • 'sage -f gap_packages'
  • 'rm -rf ~/.sage/gap/'
  • 'make'
  • 'sage -br'
sage: graphs.LivingstoneGraph()
Livingstone Graph: Graph on 266 vertices

So for the moment, I will keep on believing that this works offline. Unless you know where it could be cached?

Nathann

comment:17 in reply to: ↑ 16 ; follow-up: Changed 4 years ago by dimpase

Replying to ncohen:

So for the moment, I will keep on believing that this works offline. Unless you know where it could be cached?

RTFM?

Then, there is stuff in $SAGE_LOCAL/gap

comment:18 in reply to: ↑ 17 ; follow-ups: Changed 4 years ago by ncohen

RTFM?

Always a pleasure to work with you dima.

Then, there is stuff in $SAGE_LOCAL/gap

Yeah, I just figured this out offline. The thing is that you are not supposed to have writing access to SAGE_LOCAL/gap, so no information should be cached there. It should be done in ~/.sage/gap

Anyway, this requires internet indeed.

Nathann

Last edited 4 years ago by ncohen (previous) (diff)

comment:19 Changed 4 years ago by git

  • Commit changed from 93801c8bd1834243c34eed3bc78b0113c26439b1 to 2548e0e0802bb6ee504c87f7a03608b070c1c88c

Branch pushed to git repo; I updated commit sha1. New commits:

2548e0etrac #18774: internet

comment:20 Changed 4 years ago by git

  • Commit changed from 2548e0e0802bb6ee504c87f7a03608b070c1c88c to e977c1769111993bf016d46f0aa236ca43d9ea74

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

e977c17trac #18774: internet

comment:21 in reply to: ↑ 18 ; follow-up: Changed 4 years ago by dimpase

Replying to ncohen:

RTFM?

Always a pleasure to work with you dima

as we know, it's just an abbreviation of "Highly respected colleague, allow me most humbly point to availability of material that might alleviate doubts you have hinted at in your most valuable comments above"

:-)

comment:22 in reply to: ↑ 21 Changed 4 years ago by ncohen

as we know, it's just an abbreviation of [...]

I see. My life so far has been a lie.

Nathann

comment:23 Changed 4 years ago by git

  • Commit changed from e977c1769111993bf016d46f0aa236ca43d9ea74 to d07e879d167c82d8f304b055ee290c67e57374e0

Branch pushed to git repo; I updated commit sha1. New commits:

d07e879say why J4 is not there

comment:24 Changed 4 years ago by dimpase

Nathann, LGTM. Feel free to flip it to positive review if you're happy with my last commit.

comment:25 in reply to: ↑ 18 ; follow-up: Changed 4 years ago by dimpase

Replying to ncohen:

Then, there is stuff in $SAGE_LOCAL/gap

Yeah, I just figured this out offline. The thing is that you are not supposed to have writing access to SAGE_LOCAL/gap, so no information should be cached there. It should be done in ~/.sage/gap

so is there (where?) a bug?

comment:26 in reply to: ↑ 25 Changed 4 years ago by ncohen

so is there (where?) a bug?

Not sure. They may write to the system-wide repository if they can, and if they cannot then they write to the home gap directory.

comment:27 Changed 4 years ago by ncohen

  • Reviewers set to Dima Pasechnik
  • Status changed from needs_review to positive_review

LGTM. Feel free to flip it to positive review if you're happy with my last commit.

Works for me. Thanks!

Nathann

comment:28 Changed 4 years ago by vbraun

  • Branch changed from public/18774 to d07e879d167c82d8f304b055ee290c67e57374e0
  • Resolution set to fixed
  • Status changed from positive_review to closed
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