Opened 4 years ago

Closed 4 years ago

#19353 closed enhancement (fixed)

A (729, 448, 277, 272)-strongly regular graph

Reported by: ncohen Owned by:
Priority: major Milestone: sage-6.9
Component: graph theory Keywords:
Cc: dimpase Merged in:
Authors: Nathann Cohen Reviewers: Dima Pasechnik
Report Upstream: N/A Work issues:
Branch: c280e4d (Commits) Commit: c280e4d269104f9d5183eed42cff761b8aab623b
Dependencies: #19335 Stopgaps:

Description

As the title says. The last of the SRG advertised in the database as coming "from a two-weight code".

Change History (15)

comment:1 Changed 4 years ago by ncohen

  • Branch set to u/ncohen/19353
  • Commit set to d5f10f7e308bf0fdbe9cfd2b7cc39eab6ace8eb4
  • Status changed from new to needs_review

New commits:

d5f10f7trac #19353: A (729, 448, 277, 272)-strongly regular graph

comment:2 follow-up: Changed 4 years ago by dimpase

  • Status changed from needs_review to positive_review

OK, the last, I hope. How about (729 336 153 156 ), though? Sage says ...Penttila & Royle: projective 9-ary [42,3] code with weights 36, 39

I'm about to start complaining that all these 2-weight codes should go to where they belong to, and we just get them from sage.codes.whatever.

comment:3 in reply to: ↑ 2 ; follow-up: Changed 4 years ago by ncohen

OK, the last, I hope. How about (729 336 153 156 ), though? Sage says ...Penttila & Royle: projective 9-ary [42,3] code with weights 36, 39

Isn't that #19311?

I'm about to start complaining that all these 2-weight codes should go to where they belong to, and we just get them from sage.codes.whatever.

And you would be right to. It takes a lifetime to compile this cython module, and most of it has no reason to be cython code. Would you feel like writing this two-code module in sage.coding? It is clear that it belongs there, but given that I still do not totally understand all the meaning of all parameters in a "projective 9-ary [42,3] code with weights 36, 39", I do not feel much at ease implementing and documenting all that...

Nathann

comment:4 in reply to: ↑ 3 ; follow-up: Changed 4 years ago by dimpase

Replying to ncohen:

OK, the last, I hope. How about (729 336 153 156 ), though? Sage says ...Penttila & Royle: projective 9-ary [42,3] code with weights 36, 39

Isn't that #19311?

isn't #19311 about something different -- two-intersection code(s)?

I'm about to start complaining that all these 2-weight codes should go to where they belong to, and we just get them from sage.codes.whatever.

And you would be right to. It takes a lifetime to compile this cython module, and most of it has no reason to be cython code. Would you feel like writing this two-code module in sage.coding? It is clear that it belongs there, but given that I still do not totally understand all the meaning of all parameters in a "projective 9-ary [42,3] code with weights 36, 39", I do not feel much at ease implementing and documenting all that...

I recall having a long tread, either in email, or in some google groups, or on trac, where I explained (to myself mostly) the stuff on projective codes. I can't seem to locate it. Did I just dream about it? Or perhaps you know where to find this?

comment:5 in reply to: ↑ 4 ; follow-up: Changed 4 years ago by ncohen

isn't #19311 about something different -- two-intersection code(s)?

It's up to you. I read somewhere that two-intersection codes were equivalent to two-weight codes.

I do not mind much myself, as long as the graph is generated.

I recall having a long tread, either in email, or in some google groups, or on trac, where I explained (to myself mostly) the stuff on projective codes. I can't seem to locate it. Did I just dream about it? Or perhaps you know where to find this?

HMmmmmmm... It does not ring a bell.. Can't tell, sorry.

Nathann

comment:6 in reply to: ↑ 5 ; follow-up: Changed 4 years ago by dimpase

Replying to ncohen:

isn't #19311 about something different -- two-intersection code(s)?

It's up to you. I read somewhere that two-intersection codes were equivalent to two-weight codes.

I do not mind much myself, as long as the graph is generated.

OK, so if we knew this transformation, then no need for a new way to build graphs would be needed, right?

I recall having a long tread, either in email, or in some google groups, or on trac, where I explained (to myself mostly) the stuff on projective codes. I can't seem to locate it. Did I just dream about it? Or perhaps you know where to find this?

HMmmmmmm... It does not ring a bell.. Can't tell, sorry.

ah, it's on #18960. Good. (I checked my mailboxes, google groups, but not trac ;-))

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

OK, so if we knew this transformation, then no need for a new way to build graphs would be needed, right?

And the library would be poorer as a result. Anyway: I think that they are equivalent, but I worry that building one from the other may take a *long* time (which of course does not matter in the theory).

Nathann

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

This and #19350 need reviewer's name.

And this trac system needs automatic rejection for positive reviews without reviewer names.

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

And this trac system needs automatic rejection for positive reviews without reviewer names.

I don't necessarily agree. In my experience, the easiest would be for Dima to finally learn that he has to fill his name where it belongs. And we are talking of powerful magic here.

Natahnn

comment:10 follow-up: Changed 4 years ago by dimpase

  • Reviewers set to Dima Pasechnik

I live my life with an undiagnosed learning disability, you know...

comment:11 in reply to: ↑ 10 Changed 4 years ago by ncohen

I live my life with an undiagnosed learning disability, you know...

It was quite daring of you to pick a researcher's career :-P

Nathann

comment:12 Changed 4 years ago by vbraun

  • Status changed from positive_review to needs_work

merge conflict

comment:13 Changed 4 years ago by git

  • Commit changed from d5f10f7e308bf0fdbe9cfd2b7cc39eab6ace8eb4 to c280e4d269104f9d5183eed42cff761b8aab623b

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

c280e4dtrac #19353: Merged with 6.10.beta0

comment:14 Changed 4 years ago by ncohen

  • Status changed from needs_work to positive_review

comment:15 Changed 4 years ago by vbraun

  • Branch changed from u/ncohen/19353 to c280e4d269104f9d5183eed42cff761b8aab623b
  • Resolution set to fixed
  • Status changed from positive_review to closed
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