Opened 5 years ago

Closed 5 years ago

# Strongly Regular Graphs database

Reported by: Owned by: ncohen major sage-6.8 graph theory dimpase Nathann Cohen Dima Pasechnik N/A d1d25a0 (Commits) d1d25a03964f92c590449bebd359b21e7feaf349 #18934

This ticket implements a new module names strongly_regular_db that lets us build one example of strongly regular graph, given four integer parametes (v,k,lambda,mu).

It uses Andries Brouwer's database to return more meaningful non-existence results, and help us find which constructions are missing from the database.

With a bit of luck (and time, and work) it would be great if we could reproduce all SRG that are known to exist!

The module has a simple structure:

has a simple structure:

• A seems_feasible(v,k,l,mu) function that performs the basic artihmetic checks to figure out if (v,k,l,mu) is realizable. The 'apparently_feasible_parameters(n) returns the lists of all parameters that pass these tests for v<n. When n=1301, the set of parameters it returns is precisely those that appear on your database (this is checked in the code).
• Several functions (is_paley, is_johnson, ...) test if a given set of parameters (v,k,l,mu) can be realized with a graph of the corresponding family (a Paley graph, a Johnson graph, ...). If they can, they return the parameters of that graph so that it can be built easily.
• The main function strongly_regular_graph can be called in two ways:
• strongly_regular_graph(v,k,l,mu,existence=True) answers True if such a graph is known to exists, False if it is known to be infeasible, and Unknown otherwise.
• strongly_regular_graph(v,k,l,mu) attempts to build and return the requested graph, and returns a meaningful exception if it cannot.

This branch also updates the package 'graphs', which now ships the database in json format.

Nathann

### comment:1 Changed 5 years ago by ncohen

• Description modified (diff)
• Status changed from new to needs_review

### comment:2 Changed 5 years ago by ncohen

• Branch set to u/ncohen/18948
• Commit set to f599ffee2d99ba7a18f14667b596f921c3b7a995

New commits:

 ​f599ffe trac XXX: Strongly Regular Graphs database

### comment:3 Changed 5 years ago by git

• Commit changed from f599ffee2d99ba7a18f14667b596f921c3b7a995 to a0173e2789e7a8f79c88a77d753b48788f183e65

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

 ​a0173e2 trac #18948: Strongly Regular Graphs database

### comment:4 Changed 5 years ago by git

• Commit changed from a0173e2789e7a8f79c88a77d753b48788f183e65 to 4adcf950cd34c28460383468b17b59c695633f01

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

 ​4adcf95 trac #18948: Two missing graphs

### comment:5 follow-up: ↓ 6 Changed 5 years ago by slabbe

I think you do not need to edit module_list.py file anymore when there is no dependencies. See #15410.

### comment:6 in reply to: ↑ 5 Changed 5 years ago by ncohen

I think you do not need to edit module_list.py file anymore when there is no dependencies. See #15410.

I removed it and all doctests break because of an import problem. As I do not mind much either way personally, I leave it like that.

Nathann

### comment:7 follow-up: ↓ 8 Changed 5 years ago by dimpase

this comment landed on the wrong ticket (#18960), sorry:

Test if a Paley graph is (v,k,\lambda,\mu)-strongly regular.


Huh? Do you mean

Test whether a  (v,k,\lambda,\mu)-strongly regular graph is Paley.


All the similar docstrings have the same problem. Namely, one tests that a (v,k,l,m)-srg is BlahBlah, not the other way around...

### comment:8 in reply to: ↑ 7 Changed 5 years ago by ncohen

this comment landed on the wrong ticket (#18960), sorry:

Test if a Paley graph is (v,k,\lambda,\mu)-strongly regular.


Huh? Do you mean

Test whether a  (v,k,\lambda,\mu)-strongly regular graph is Paley.


To me your phrasing also sounds incorrect, as it seems to test whether "any (v,k,l,mu)-strongly regular graph is a Paley graph".

What about replacing 'a' by 'some' or 'any'?

Test if any Paley graph is (v,k,l,mu)-strongly regular


Nathann

Version 0, edited 5 years ago by ncohen (next)

### comment:9 Changed 5 years ago by git

• Commit changed from 4adcf950cd34c28460383468b17b59c695633f01 to a9280c9ae07f2703e7d004d463a77d8e6482025f

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

 ​8f25493 trac #18948: Merged with 6.9.beta0 ​a9280c9 trac #18948: Rephrasing the doc

### comment:10 follow-up: ↓ 11 Changed 5 years ago by dimpase

Do you really want to keep mu as a required by functions parameter? I would rather get rid of it, for it is a simple computation to find mu given the 1st three parameters.

### comment:11 in reply to: ↑ 10 Changed 5 years ago by ncohen

Do you really want to keep mu as a required by functions parameter? I would rather get rid of it, for it is a simple computation to find mu given the 1st three parameters.

I prefer to keep it, for it belongs to the definition of strongly regular graphs. I don't see anything wrong it making it optional: we can replace 'None' by the computed value if necessary.

Nathann

### comment:12 Changed 5 years ago by git

• Commit changed from a9280c9ae07f2703e7d004d463a77d8e6482025f to 0ed84411d7d2eb896530a961255739939e3a7609

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

 ​0ed8441 trac #18948: guess mu

### comment:13 follow-up: ↓ 14 Changed 5 years ago by git

• Commit changed from 0ed84411d7d2eb896530a961255739939e3a7609 to cf8f2dad1cd90ff5aaa0cec15a25f87c64289719

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

 ​cf8f2da trac #18948: guess mu

### comment:14 in reply to: ↑ 13 ; follow-up: ↓ 15 Changed 5 years ago by dimpase

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

 ​cf8f2da trac #18948: guess mu

How about functions like is_paley()? They also do not need mu...

By the way, what is the point of doing return (lambda q : PaleyGraph(q),v) instead of return PaleyGraph(v) ?

### comment:15 in reply to: ↑ 14 Changed 5 years ago by ncohen

How about functions like is_paley()? They also do not need mu...

If you think that this feature would be useful, I have nothing against your adding it in another ticket. I do not see the point, as those functions are not even meant to be called directly by users, who can do so with 'strongly_regular_graph' (which can automatically guess 'mu' if needed).

By the way, what is the point of doing return (lambda q : PaleyGraph(q),v) instead of return PaleyGraph(v) ?

That's in order to be able to tell if the construction *can* be done without doing it (which can take quite some time). Very useful to know which entries Sage can build to compare it to the list of those that are known to exist. I used a design similar to the one used in sage.combinat.designs.orthogonal_arrays_find_construction, where many functions exist to *guess* the parameters of some constructions (exactly like it is done here). With these design, knowing if something can be built and getting the data to build it is done in the same operation. There are two advantages:

1) No need of a 'exists=True' optional keyword when you call the function 2) No 'if exists' everywhere in the code's function, to return 'True' instead of returning the graph 3) If you want to test the existence, THEN build the graph, you do not call the function twice with different parameters (which would not use the function's cache, and so you compute the decomposition twice).

Admittedly, the functions of the design code are computationally much more expensive than those.

Nathann

### comment:16 Changed 5 years ago by dimpase

it seems that

cdef eigenvalues(int v,int k,int l,int mu)


only returns correct results for the non-Paley (non-conference) case (i.e. the case where the eigenvalues are not integer).

This should be documented, at least.

Last edited 5 years ago by dimpase (previous) (diff)

### comment:17 Changed 5 years ago by git

• Commit changed from cf8f2dad1cd90ff5aaa0cec15a25f87c64289719 to aed4022eb9ea74be3cb3acab1ff9b1570b01c6e8

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

 ​aed4022 trac #18948: DOcstring

### comment:18 Changed 5 years ago by git

• Commit changed from aed4022eb9ea74be3cb3acab1ff9b1570b01c6e8 to 4f51703c4e63909516d4711714a5429cfd4f5050

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

 ​4f51703 trac #18948: DOcstring

### comment:19 follow-up: ↓ 20 Changed 5 years ago by dimpase

there are easy to implement necessary conditions on parameters which don't seem to be there, e.g. Krein conditions, absolute bound, etc; see 9.1.8 in http://www.win.tue.nl/~aeb/2WF02/spectra.pdf

I don't mind them to be added in a follow-up ticket, but it has to be done, I think.

### comment:20 in reply to: ↑ 19 ; follow-up: ↓ 25 Changed 5 years ago by ncohen

I don't mind them to be added in a follow-up ticket, but it has to be done, I think.

I know, I already have plans for that. I planned to do it after #18960.

Nathann

### comment:21 Changed 5 years ago by dimpase

• Status changed from needs_review to positive_review

Thanks !

### comment:23 Changed 5 years ago by git

• Commit changed from 4f51703c4e63909516d4711714a5429cfd4f5050 to a75774fa9f6168b4f0e34c6cdd93496f7283b179
• Status changed from positive_review to needs_review

Branch pushed to git repo; I updated commit sha1 and set ticket back to needs_review. New commits:

 ​a75774f trac #18948: take into account the BIBD from #18934

### comment:24 Changed 5 years ago by ncohen

• Status changed from needs_review to positive_review

### comment:25 in reply to: ↑ 20 Changed 5 years ago by ncohen

I don't mind them to be added in a follow-up ticket, but it has to be done, I think.

I know, I already have plans for that. I planned to do it after #18960.

Done at #18982.

Nathann

### comment:26 Changed 5 years ago by vbraun

• Status changed from positive_review to needs_work

Reviewer name

### comment:27 Changed 5 years ago by dimpase

• Reviewers set to Dima Pasechnik

### comment:28 Changed 5 years ago by ncohen

• Status changed from needs_work to positive_review

### comment:29 follow-up: ↓ 30 Changed 5 years ago by dimpase

these graphs, O(2d-1,q), are available, but not known to your DB:

sage: o=graphs.OrthogonalPolarGraph(5,4)
sage: o.is_strongly_regular(parameters=True)
(85, 20, 3, 5)
sage: graphs.strongly_regular_graph(85, 20, 3, 5)
---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
<ipython-input-29-152b95dceef4> in <module>()
----> 1 graphs.strongly_regular_graph(Integer(85), Integer(20), Integer(3), Integer(5))

/home/dima/software/sage/src/sage/graphs/strongly_regular_db.pyx in sage.graphs.strongly_regular_db.strongly_regular_graph (build/cythonized/sage/graphs/strongly_regular_db.c:12463)()
1061             if existence:
1062                 return True
-> 1063             raise RuntimeError(("Andries Brouwer's database claims that such a "+
1064                                 "({},{},{},{})-strongly regular graph exists, but "+
1065                                 "Sage does not know how to build it. If *you* do, "+

RuntimeError: Andries Brouwer's database claims that such a (85,20,3,5)-strongly regular graph exists, but Sage does not know how to build it. If *you* do, please get in touch with us on sage-devel!
sage:

Last edited 5 years ago by dimpase (previous) (diff)

### comment:30 in reply to: ↑ 29 Changed 5 years ago by ncohen

these graphs, O(2d-1,q), are available, but not known to your DB:

Done at #18988

sage: graphs.strongly_regular_graph(85, 20, 3, 5)
Orthogonal Polar Graph O(5, 4): Graph on 85 vertices


Nathann

### comment:31 Changed 5 years ago by git

• Commit changed from a75774fa9f6168b4f0e34c6cdd93496f7283b179 to d1d25a03964f92c590449bebd359b21e7feaf349
• Status changed from positive_review to needs_review

Branch pushed to git repo; I updated commit sha1 and set ticket back to needs_review. New commits:

 ​a0cac66 trac #18934: new BIBD: (91,7,1), (66,6,1), (76,6,1), (96,6,1) ​e46b058 trac #18934: New (v,6,1)-BIBD with v=201 ​a04a2fb trac #18934: Broken doctests ​11e9f1f trac #18934: Last one -> (126,6,1)-BIBD ​796bcde trac #18934: Merged with 6.8.rc1 ​6ed1abf trac #18934: Fixed credits ​62ce12c trac #18934: Merged with beta0 ​f4f5566 trac #18948: Merge with updated #18934 ​d1d25a0 trac #18948: Broken doctest

### comment:32 Changed 5 years ago by ncohen

• Dependencies set to #18934
• Status changed from needs_review to positive_review

### comment:33 follow-up: ↓ 35 Changed 5 years ago by vbraun

• Status changed from positive_review to needs_work

With #18988, #18960, and #18948:

sage -t --long src/sage/graphs/strongly_regular_db.pyx
**********************************************************************
File "src/sage/graphs/strongly_regular_db.pyx", line 1209, in sage.graphs.strongly_regular_db._check_database
Failed example:
_check_database() # long time
Expected:
Sage cannot build a (45   22   10   11  ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Mathon78">Mathon</a>; 2-graph*
...
In Andries Brouwer's database:
- 448 impossible entries
- 2950 undecided entries
- 1140 realizable entries (Sage misses 298 of them)
Got:
Sage cannot build a (45   22   10   11  ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Mathon78">Mathon</a>; 2-graph*
Sage cannot build a (96   19   2    4   ) that exists. Comment from Brouwer's database: Haemers(4); <a href="srgtabrefs.html#Muzychuk07">Muzychuk S6</a> (n=4,d=2); <a href="srgtabrefs.html#Brouwer_et_al03">Brouwer-Koolen-Klin</a>; <a href="srgtabrefs.html#Golemac_et_al06">Golemac et al.</a>
Sage cannot build a (96   20   4    4   ) that exists. Comment from Brouwer's database: GQ(5,3); <a href="srgtabrefs.html#Brouwer_et_al03">Brouwer-Koolen-Klin</a>; <a href="srgtabrefs.html#Golemac_et_al06">Golemac et al.</a>
Sage cannot build a (96   75   58   60  ) that exists. Comment from Brouwer's database:
Sage cannot build a (96   76   60   60  ) that exists. Comment from Brouwer's database:
Sage cannot build a (100  44   18   20  ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#JorgensenKlin03">Jrgensen-Klin</a>; RSHCD<sup></sup>; 2-graph
Sage cannot build a (100  45   20   20  ) that exists. Comment from Brouwer's database: OA(10,5)?; RSHCD<sup>+</sup>; 2-graph
Sage cannot build a (100  54   28   30  ) that exists. Comment from Brouwer's database: OA(10,6)?; 2-graph
Sage cannot build a (100  55   30   30  ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (105  32   4    12  ) that exists. Comment from Brouwer's database: Aut L(3,4) on flags (rk 4) - <a href="srgtabrefs.html#GoethalsSeidel70">Goethals & Seidel</a>, unique by <a href="srgtabrefs.html#Coolsaet05">Coolsaet</a>
Sage cannot build a (105  72   51   45  ) that exists. Comment from Brouwer's database:
Sage cannot build a (120  42   8    18  ) that exists. Comment from Brouwer's database: L(3,4) on Baer subplanes (rk 5), unique by <a href="srgtabrefs.html#DegraerCoolsaet08">Degraer & Coolsaet</a>
Sage cannot build a (120  51   18   24  ) that exists. Comment from Brouwer's database: NO<sup></sup>(5,4); 2-graph
Sage cannot build a (120  56   28   24  ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (120  63   30   36  ) that exists. Comment from Brouwer's database: dist. 2 in J(10,3) - Mathon; NO<sup>+</sup>(8,2); Goethals-Seidel(3,7); pg(7,8,4) - <a href="srgtabrefs.html#Cohen81">Cohen</a>; see also <a href="srgtabrefs.html#DeClerckDelanote00">De Clerck & Delanote</a>; 2-graph
Sage cannot build a (120  68   40   36  ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (120  77   52   44  ) that exists. Comment from Brouwer's database: Witt: intersection-3 graph of a 2-(21,7,12) design with block intersections 1, 3
Sage cannot build a (122  55   24   25  ) that exists. Comment from Brouwer's database: switch OA(11,6)+*; switch skewhad<sup>2</sup>+*; 2-graph
Sage cannot build a (122  66   35   36  ) that exists. Comment from Brouwer's database: S(2,6,61)?; 2-graph
Sage cannot build a (125  28   3    7   ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Godsil92">Godsil</a>(q=5,r=3); GQ(4,6)
Sage cannot build a (125  52   15   26  ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Godsil92">Godsil</a>(q=5,r=2); pg(4,12,2)?; 2-graph*
Sage cannot build a (125  72   45   36  ) that exists. Comment from Brouwer's database: 2-graph*
Sage cannot build a (125  96   74   72  ) that exists. Comment from Brouwer's database:
Sage cannot build a (126  25   8    4   ) that exists. Comment from Brouwer's database: dist. 1 or 4 in J(9,4) - Mathon, Buekenhout & Hubaut
Sage cannot build a (126  45   12   18  ) that exists. Comment from Brouwer's database: NO<sup></sup>(6,3); pg(5,8,2)?
Sage cannot build a (126  50   13   24  ) that exists. Comment from Brouwer's database: Goethals - unique by <a href="srgtabrefs.html#CoolsaetDegraer08">Coolsaet & Degraer</a>; 2-graph
Sage cannot build a (126  60   33   24  ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (126  65   28   39  ) that exists. Comment from Brouwer's database: pg(5,12,3)?; Taylor 2-graph for U<sub>3</sub>(5)
Sage cannot build a (126  75   48   39  ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (126  80   52   48  ) that exists. Comment from Brouwer's database:
Sage cannot build a (126  100  78   84  ) that exists. Comment from Brouwer's database:
Sage cannot build a (136  60   24   28  ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (136  63   30   28  ) that exists. Comment from Brouwer's database: NO<sup></sup>(8,2); 2-graph
Sage cannot build a (136  72   36   40  ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (136  75   42   40  ) that exists. Comment from Brouwer's database: NO<sup>+</sup>(5,4); 2-graph
Sage cannot build a (144  39   6    12  ) that exists. Comment from Brouwer's database: L<sub>3</sub>(3) (rk 8)
Sage cannot build a (144  65   28   30  ) that exists. Comment from Brouwer's database: RSHCD<sup></sup>; 2-graph
Sage cannot build a (144  78   42   42  ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (144  104  76   72  ) that exists. Comment from Brouwer's database:
Sage cannot build a (165  36   3    9   ) that exists. Comment from Brouwer's database: U(5,2) polar graph; GQ(4,8)
Sage cannot build a (165  128  100  96  ) that exists. Comment from Brouwer's database:
Sage cannot build a (170  78   35   36  ) that exists. Comment from Brouwer's database: switch OA(13,7)+*; 2-graph
Sage cannot build a (170  91   48   49  ) that exists. Comment from Brouwer's database: S(2,7,85)?; 2-graph
Sage cannot build a (175  30   5    5   ) that exists. Comment from Brouwer's database: GQ(6,4)
Sage cannot build a (175  72   20   36  ) that exists. Comment from Brouwer's database: edges of Hoffman-Singleton graph - Haemers; pg(4,17,2) - <a href="srgtabrefs.html#Haemers81">Haemers</a>; 2-graph*
Sage cannot build a (175  102  65   51  ) that exists. Comment from Brouwer's database: 2-graph*
Sage cannot build a (175  144  118  120 ) that exists. Comment from Brouwer's database:
Sage cannot build a (176  40   12   8   ) that exists. Comment from Brouwer's database: pg(10,3,2) does not exist (Absolute bound for line graph)
Sage cannot build a (176  49   12   14  ) that exists. Comment from Brouwer's database: Higman symmetric 2-design; pg(7,6,2)?
Sage cannot build a (176  70   18   34  ) that exists. Comment from Brouwer's database: S(4,7,23)S(3,6,22) - M<sub>22</sub>/Alt(7); unique by Coolsaet & Degraer; 2-graph
Sage cannot build a (176  85   48   34  ) that exists. Comment from Brouwer's database: Haemers; 2-graph
Sage cannot build a (176  90   38   54  ) that exists. Comment from Brouwer's database: pg(5,17,3)?; 2-graph
Sage cannot build a (176  105  68   54  ) that exists. Comment from Brouwer's database: Witt 3-(22,7,4): intersection-3 graph of a quasisymmetric 2-(22,7,16) design with intersection numbers 1, 3; 2-graph
Sage cannot build a (176  126  90   90  ) that exists. Comment from Brouwer's database:
Sage cannot build a (176  135  102  108 ) that exists. Comment from Brouwer's database: NU(5,2)
Sage cannot build a (196  90   40   42  ) that exists. Comment from Brouwer's database: RSHCD<sup></sup>; 2-graph
Sage cannot build a (196  91   42   42  ) that exists. Comment from Brouwer's database: OA(14,7)?; RSHCD<sup>+</sup>; 2-graph
Sage cannot build a (196  104  54   56  ) that exists. Comment from Brouwer's database: OA(14,8)?; 2-graph
Sage cannot build a (196  105  56   56  ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (209  100  45   50  ) that exists. Comment from Brouwer's database: pg(10,9,5)?; 2-graph*
Sage cannot build a (209  108  57   54  ) that exists. Comment from Brouwer's database: 2-graph*
Sage cannot build a (210  99   48   45  ) that exists. Comment from Brouwer's database: Sym(7) - Klin; 2-graph
Sage cannot build a (210  110  55   60  ) that exists. Comment from Brouwer's database: pg(11,9,6)?; 2-graph
Sage cannot build a (220  84   38   28  ) that exists. Comment from Brouwer's database: Tonchev: intersection-3 graph of a 2-(45,9,8) design with block intersections 1, 3
Sage cannot build a (220  135  78   90  ) that exists. Comment from Brouwer's database: pg(9,14,6)?
Sage cannot build a (225  98   43   42  ) that exists. Comment from Brouwer's database: OA(15,7)?; Pasechnik(15)
Sage cannot build a (225  112  55   56  ) that exists. Comment from Brouwer's database: skewhad$^2$; OA(15,8)?; 2-graph*
Sage cannot build a (225  126  69   72  ) that exists. Comment from Brouwer's database: OA(15,9)?
Sage cannot build a (226  105  48   49  ) that exists. Comment from Brouwer's database: switch skewhad<sup>2</sup>+*; 2-graph
Sage cannot build a (226  120  63   64  ) that exists. Comment from Brouwer's database: S(2,8,113)?; 2-graph
Sage cannot build a (243  22   1    2   ) that exists. Comment from Brouwer's database: 3<sup>5</sup>.2.M<sub>11</sub> (rk 3) - Berlekamp-vanLint-Seidel; Golay code: projective ternary [11,5] code with weights 6, 9
Sage cannot build a (243  110  37   60  ) that exists. Comment from Brouwer's database: 3<sup>5</sup>.2.M<sub>11</sub> (rk 3) - Delsarte; projective ternary [55,5] code with weights 36, 45
Sage cannot build a (243  132  81   60  ) that exists. Comment from Brouwer's database:
Sage cannot build a (243  220  199  200 ) that exists. Comment from Brouwer's database:
Sage cannot build a (253  112  36   60  ) that exists. Comment from Brouwer's database: S(4,7,23) - M<sub>23</sub>
Sage cannot build a (253  140  87   65  ) that exists. Comment from Brouwer's database: Witt 4-(23,7,1): intersection-3 graph of a 2-(23,7,21) design with block intersections 1, 3
Sage cannot build a (256  68   12   20  ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Brouwer85">Brouwer</a>(q=2,d=4,e=2,-); projective binary [68,8] code with weights 32, 40
Sage cannot build a (256  85   24   30  ) that exists. Comment from Brouwer's database: vanLint-Schrijver(1); CK - CY1: projective binary [85,8] code with weights 40, 48
Sage cannot build a (256  102  38   42  ) that exists. Comment from Brouwer's database: 2<sup>8</sup>.L<sub>2</sub>(17) (rk 3) - Liebeck; vanLint-Schrijver(2); CK - CY1: projective 4-ary [34,4] code with weights 24, 28
Sage cannot build a (256  153  92   90  ) that exists. Comment from Brouwer's database: vanLint-Schrijver(3)
Sage cannot build a (256  170  114  110 ) that exists. Comment from Brouwer's database: vanLint-Schrijver(2)
Sage cannot build a (256  187  138  132 ) that exists. Comment from Brouwer's database:
Sage cannot build a (276  135  78   54  ) that exists. Comment from Brouwer's database: Conway-Goethals&Seidel; 2-graph
Sage cannot build a (276  140  58   84  ) that exists. Comment from Brouwer's database: pg(5,27,3)?; 2-graph
Sage cannot build a (279  128  52   64  ) that exists. Comment from Brouwer's database: pg(8,15,4)?; 2-graph*
Sage cannot build a (279  150  85   75  ) that exists. Comment from Brouwer's database: 2-graph*
Sage cannot build a (280  36   8    4   ) that exists. Comment from Brouwer's database: J<sub>2</sub> / 3PGL<sub>2</sub>(9) (rk 4); U(4,3) polar graph; GQ(9,3)
Sage cannot build a (280  117  44   52  ) that exists. Comment from Brouwer's database: pg(9,12,4)?
Sage cannot build a (280  162  96   90  ) that exists. Comment from Brouwer's database: Sym(9) (rk 5) - Mathon & Rosa
Sage cannot build a (280  243  210  216 ) that exists. Comment from Brouwer's database:
Sage cannot build a (290  136  63   64  ) that exists. Comment from Brouwer's database: switch OA(17,9)+*; 2-graph
Sage cannot build a (290  153  80   81  ) that exists. Comment from Brouwer's database: S(2,9,145)?; 2-graph
Sage cannot build a (297  40   7    5   ) that exists. Comment from Brouwer's database: dual polar graph of lines in U<sub>5</sub>(2); GQ(8,4)
Sage cannot build a (297  256  220  224 ) that exists. Comment from Brouwer's database:
Sage cannot build a (300  65   10   15  ) that exists. Comment from Brouwer's database: NO<sup>,orth</sup>(5,5)
Sage cannot build a (300  104  28   40  ) that exists. Comment from Brouwer's database: NO<sup></sup>(5,5)
Sage cannot build a (300  195  130  120 ) that exists. Comment from Brouwer's database:
Sage cannot build a (300  234  183  180 ) that exists. Comment from Brouwer's database:
Sage cannot build a (323  160  78   80  ) that exists. Comment from Brouwer's database: pg(16,9,8)?; 2-graph*
Sage cannot build a (323  162  81   81  ) that exists. Comment from Brouwer's database: S(2,9,153)?; 2-graph*
Sage cannot build a (324  152  70   72  ) that exists. Comment from Brouwer's database: RSHCD<sup></sup>; 2-graph
Sage cannot build a (324  153  72   72  ) that exists. Comment from Brouwer's database: OA(18,9)?; RSHCD<sup>+</sup>; 2-graph
Sage cannot build a (324  170  88   90  ) that exists. Comment from Brouwer's database: OA(18,10)?; 2-graph
Sage cannot build a (324  171  90   90  ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (325  60   15   10  ) that exists. Comment from Brouwer's database: NO<sup>+,orth</sup>(5,5); pg(12,4,2)?
Sage cannot build a (325  144  68   60  ) that exists. Comment from Brouwer's database: NO<sup>+</sup>(5,5)
Sage cannot build a (325  180  95   105 ) that exists. Comment from Brouwer's database: pg(12,14,7)?
Sage cannot build a (325  264  213  220 ) that exists. Comment from Brouwer's database:
Sage cannot build a (343  54   5    9   ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Godsil92">Godsil</a>(q=7,r=4); GQ(6,8)
Sage cannot build a (343  150  53   75  ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Godsil92">Godsil</a>(q=7,r=2); pg(6,24,3)?; 2-graph*
Sage cannot build a (343  192  116  96  ) that exists. Comment from Brouwer's database: 2-graph*
Sage cannot build a (343  288  242  240 ) that exists. Comment from Brouwer's database:
Sage cannot build a (344  168  92   72  ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (344  175  78   100 ) that exists. Comment from Brouwer's database: pg(7,24,4)?; Taylor 2-graph for U<sub>3</sub>(7)
Sage cannot build a (351  126  45   45  ) that exists. Comment from Brouwer's database:
Sage cannot build a (351  224  142  144 ) that exists. Comment from Brouwer's database: NO<sup></sup>(7,3)
Sage cannot build a (362  171  80   81  ) that exists. Comment from Brouwer's database: switch OA(19,10)+*; switch skewhad<sup>2</sup>+*; 2-graph
Sage cannot build a (362  190  99   100 ) that exists. Comment from Brouwer's database: S(2,10,181)?; 2-graph
Sage cannot build a (378  52   1    8   ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#CossidentePenttila05">Cossidente-Penttila hemisystem</a> in PG(3,5<sup>2</sup>)
Sage cannot build a (378  116  34   36  ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Muzychuk07">Muzychuk S6</a> (n=3,d=3)
Sage cannot build a (378  117  36   36  ) that exists. Comment from Brouwer's database: pg(13,8,4)?
Sage cannot build a (378  260  178  180 ) that exists. Comment from Brouwer's database: NO<sup>+</sup>(7,3)
Sage cannot build a (378  261  180  180 ) that exists. Comment from Brouwer's database:
Sage cannot build a (378  325  280  275 ) that exists. Comment from Brouwer's database:
Sage cannot build a (399  198  97   99  ) that exists. Comment from Brouwer's database: pg(18,10,9)?; 2-graph*
Sage cannot build a (399  200  100  100 ) that exists. Comment from Brouwer's database: S(2,10,190)?; 2-graph*
Sage cannot build a (400  189  88   90  ) that exists. Comment from Brouwer's database: RSHCD<sup></sup>; 2-graph
Sage cannot build a (400  190  90   90  ) that exists. Comment from Brouwer's database: OA(20,10)?; RSHCD<sup>+</sup>; 2-graph
Sage cannot build a (400  209  108  110 ) that exists. Comment from Brouwer's database: OA(20,11)?; Goethals-Seidel(2,19); 2-graph
Sage cannot build a (400  210  110  110 ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (416  100  36   20  ) that exists. Comment from Brouwer's database: G<sub>2</sub>(4).2 / J<sub>2</sub>.2; subconstituent of Suz graph
Sage cannot build a (416  315  234  252 ) that exists. Comment from Brouwer's database: pg(15,20,12)?
Sage cannot build a (441  56   7    7   ) that exists. Comment from Brouwer's database: GQ(8,6)
Sage cannot build a (441  220  109  110 ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Mathon78">Mathon</a>; OA(21,11)?; 2-graph*
Sage cannot build a (441  384  334  336 ) that exists. Comment from Brouwer's database:
Sage cannot build a (496  240  120  112 ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (496  255  126  136 ) that exists. Comment from Brouwer's database: NO<sup>+</sup>(10,2); Goethals-Seidel(3,15); pg(15,16,8)?; 2-graph
Sage cannot build a (512  70   6    10  ) that exists. Comment from Brouwer's database: GQ(7,9); from a hyperoval: projective 8-ary [10,3] code with weights 8, 10
Sage cannot build a (512  73   12   10  ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#FiedlerKlin98">Fiedler-Klin</a>; <a href="srgtabrefs.html#Kohnert07">Kohnert</a>: projective binary [73,9] code with weights 32, 40
Sage cannot build a (512  133  24   38  ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Godsil92">Godsil</a>(q=8,r=3); pg(7,18,2)?
Sage cannot build a (512  196  60   84  ) that exists. Comment from Brouwer's database: pg(7,27,3); projective 8-ary [28,3] code with weights 24, 28
Sage cannot build a (512  219  106  84  ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#FiedlerKlin98">Fiedler-Klin</a>; projective binary [219,9] code with weights 96, 112
Sage cannot build a (512  292  156  180 ) that exists. Comment from Brouwer's database:
Sage cannot build a (512  315  202  180 ) that exists. Comment from Brouwer's database:
Sage cannot build a (512  378  282  270 ) that exists. Comment from Brouwer's database:
Sage cannot build a (512  438  374  378 ) that exists. Comment from Brouwer's database:
Sage cannot build a (512  441  380  378 ) that exists. Comment from Brouwer's database:
Sage cannot build a (528  255  126  120 ) that exists. Comment from Brouwer's database: NO<sup></sup>(10,2); <a href="srgtabrefs.html#Muzychuk07">Muzychuk S2</a> (r=4); 2-graph
Sage cannot build a (528  272  136  144 ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (530  253  120  121 ) that exists. Comment from Brouwer's database: switch OA(23,12)+*; switch skewhad<sup>2</sup>+*; 2-graph
Sage cannot build a (530  276  143  144 ) that exists. Comment from Brouwer's database: S(2,12,265)?; 2-graph
Sage cannot build a (539  250  105  125 ) that exists. Comment from Brouwer's database: pg(10,24,5)?; 2-graph*
Sage cannot build a (539  288  162  144 ) that exists. Comment from Brouwer's database: 2-graph*
Sage cannot build a (540  224  88   96  ) that exists. Comment from Brouwer's database: NU(4,3); pg(14,15,6)?
Sage cannot build a (540  264  138  120 ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (540  275  130  150 ) that exists. Comment from Brouwer's database: Goethals-Seidel(5,11); pg(11,24,6)?; 2-graph
Sage cannot build a (540  315  186  180 ) that exists. Comment from Brouwer's database:
Sage cannot build a (560  208  72   80  ) that exists. Comment from Brouwer's database: Sz(8) (rk 17); pg(13,15,5)?
Sage cannot build a (560  351  222  216 ) that exists. Comment from Brouwer's database:
Sage cannot build a (575  286  141  143 ) that exists. Comment from Brouwer's database: pg(22,12,11)?; 2-graph*
Sage cannot build a (575  288  144  144 ) that exists. Comment from Brouwer's database: S(2,12,276)?; 2-graph*
Sage cannot build a (576  275  130  132 ) that exists. Comment from Brouwer's database: RSHCD<sup></sup>; 2-graph
Sage cannot build a (576  276  132  132 ) that exists. Comment from Brouwer's database: OA(24,12)?; RSHCD<sup>+</sup>; 2-graph
Sage cannot build a (576  299  154  156 ) that exists. Comment from Brouwer's database: OA(24,13)?; Goethals-Seidel(2,23); 2-graph
Sage cannot build a (576  300  156  156 ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (625  156  29   42  ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Bouyukliev_et_al06">Bouyukliev-Fack-Willems-Winne</a>: projective 5-ary [39,4] code with weights 30, 35
Sage cannot build a (625  208  63   72  ) that exists. Comment from Brouwer's database: vanLint-Schrijver(1); CK - CY1: projective 5-ary [52,4] code with weights 40, 45
Sage cannot build a (625  416  279  272 ) that exists. Comment from Brouwer's database: vanLint-Schrijver(2)
Sage cannot build a (625  468  353  342 ) that exists. Comment from Brouwer's database:
Sage cannot build a (626  300  143  144 ) that exists. Comment from Brouwer's database: switch OA(25,13)+*; 2-graph
Sage cannot build a (626  325  168  169 ) that exists. Comment from Brouwer's database: S(2,13,313)?; 2-graph
Sage cannot build a (630  85   20   10  ) that exists. Comment from Brouwer's database: pg(17,4,2) - <a href="srgtabrefs.html#Haemers81">Haemers</a>
Sage cannot build a (630  544  468  480 ) that exists. Comment from Brouwer's database:
Sage cannot build a (640  71   6    8   ) that exists. Comment from Brouwer's database: Haemers(8); <a href="srgtabrefs.html#Muzychuk07">Muzychuk S6</a> (n=8,d=2)
Sage cannot build a (640  72   8    8   ) that exists. Comment from Brouwer's database: GQ(9,7)
Sage cannot build a (640  567  502  504 ) that exists. Comment from Brouwer's database:
Sage cannot build a (640  568  504  504 ) that exists. Comment from Brouwer's database:
Sage cannot build a (672  176  40   48  ) that exists. Comment from Brouwer's database: pg(11,15,3)?
Sage cannot build a (672  495  366  360 ) that exists. Comment from Brouwer's database: NU(6,2)
Sage cannot build a (675  336  166  168 ) that exists. Comment from Brouwer's database: pg(24,13,12)?; 2-graph*
Sage cannot build a (675  338  169  169 ) that exists. Comment from Brouwer's database: S(2,13,325)?; 2-graph*
Sage cannot build a (676  325  156  156 ) that exists. Comment from Brouwer's database: OA(26,13)?; RSHCD<sup>+</sup>; 2-graph
Sage cannot build a (676  350  180  182 ) that exists. Comment from Brouwer's database: OA(26,14)?; 2-graph
Sage cannot build a (693  180  51   45  ) that exists. Comment from Brouwer's database: U<sub>6</sub>(2) / 2<sup>9</sup>.U<sub>4</sub>(2); subconstituent of Fi<sub>22</sub> graph; U(6,2) polar graph; pg(20,8,5)?
Sage cannot build a (693  512  376  384 ) that exists. Comment from Brouwer's database:
Sage cannot build a (729  88   7    11  ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Godsil92">Godsil</a>(q=9,r=5); GQ(8,10)
Sage cannot build a (729  112  1    20  ) that exists. Comment from Brouwer's database: 3<sup>6</sup>.2.L3(4) (rk 3) - <a href="srgtabrefs.html#Hill73">Hill</a> cap: projective ternary [56,6] code with weights 36, 45; <a href="srgtabrefs.html#BondarenkoRadchenko12">Bondarenko-Radchenko</a>
Sage cannot build a (729  168  27   42  ) that exists. Comment from Brouwer's database: pg(8,20,2) - <a href="srgtabrefs.html#DeClerck_et_al02">Mathon</a>; <a href="srgtabrefs.html#Gulliver96">Gulliver</a>: projective ternary [84,6] code with weights 54, 63
Sage cannot build a (729  252  81   90  ) that exists. Comment from Brouwer's database: VNO<sup></sup>(6,3) affine polar graph; projective ternary [126,6] code with weights 81, 90
Sage cannot build a (729  280  103  110 ) that exists. Comment from Brouwer's database: 35-set of type (2,5) in PG(2,9) - <a href="srgtabrefs.html#deResmini87">De Resmini</a>: projective 9-ary [35,3] code with weights 30, 33
Sage cannot build a (729  308  127  132 ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Gulliver96a">Gulliver</a>: projective ternary [154,6] code with weights 99, 108
Sage cannot build a (729  328  127  164 ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Godsil92">Godsil</a>(q=9,r=2); pg(8,40,4)?; 2-graph*
Sage cannot build a (729  336  153  156 ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#PenttilaRoyle95">Penttila & Royle</a>: projective 9-ary [42,3] code with weights 36, 39
Sage cannot build a (729  392  211  210 ) that exists. Comment from Brouwer's database:
Sage cannot build a (729  400  235  200 ) that exists. Comment from Brouwer's database: 2-graph*
Sage cannot build a (729  420  243  240 ) that exists. Comment from Brouwer's database:
Sage cannot build a (729  448  277  272 ) that exists. Comment from Brouwer's database:
Sage cannot build a (729  476  313  306 ) that exists. Comment from Brouwer's database:
Sage cannot build a (729  560  433  420 ) that exists. Comment from Brouwer's database:
Sage cannot build a (729  616  523  506 ) that exists. Comment from Brouwer's database:
Sage cannot build a (729  640  562  560 ) that exists. Comment from Brouwer's database:
Sage cannot build a (730  351  168  169 ) that exists. Comment from Brouwer's database: switch OA(27,14)+*; switch skewhad<sup>2</sup>+*; 2-graph
Sage cannot build a (730  360  195  160 ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (730  369  168  205 ) that exists. Comment from Brouwer's database: pg(9,40,5)?; Taylor 2-graph for U<sub>3</sub>(9)
Sage cannot build a (730  378  195  196 ) that exists. Comment from Brouwer's database: S(2,14,365)?; 2-graph
Sage cannot build a (765  192  48   48  ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#IoninKharaghani03">Ionin-Kharaghani</a>; pg(16,11,4)?
Sage cannot build a (765  572  427  429 ) that exists. Comment from Brouwer's database:
Sage cannot build a (779  378  177  189 ) that exists. Comment from Brouwer's database: pg(18,20,9)?; 2-graph*
Sage cannot build a (779  400  210  200 ) that exists. Comment from Brouwer's database: 2-graph*
Sage cannot build a (780  380  190  180 ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (780  399  198  210 ) that exists. Comment from Brouwer's database: Goethals-Seidel(3,19); pg(19,20,10)?; 2-graph
Sage cannot build a (783  390  193  195 ) that exists. Comment from Brouwer's database: pg(26,14,13)?; 2-graph*
Sage cannot build a (783  392  196  196 ) that exists. Comment from Brouwer's database: S(2,14,378)?; 2-graph*
Sage cannot build a (784  243  82   72  ) that exists. Comment from Brouwer's database: Mathon; OA(28,9)?
Sage cannot build a (784  270  98   90  ) that exists. Comment from Brouwer's database: Mathon; OA(28,10)?
Sage cannot build a (784  297  116  110 ) that exists. Comment from Brouwer's database: Mathon; OA(28,11)?
Sage cannot build a (784  377  180  182 ) that exists. Comment from Brouwer's database: RSHCD<sup></sup>; 2-graph
Sage cannot build a (784  378  182  182 ) that exists. Comment from Brouwer's database: OA(28,14)?; RSHCD<sup>+</sup>; 2-graph
Sage cannot build a (784  405  208  210 ) that exists. Comment from Brouwer's database: OA(28,15)?; Goethals-Seidel(2,27); 2-graph
Sage cannot build a (784  406  210  210 ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (784  486  298  306 ) that exists. Comment from Brouwer's database: OA(28,18)?
Sage cannot build a (784  513  332  342 ) that exists. Comment from Brouwer's database: OA(28,19)?
Sage cannot build a (784  540  368  380 ) that exists. Comment from Brouwer's database: OA(28,20)?
Sage cannot build a (842  406  195  196 ) that exists. Comment from Brouwer's database: switch OA(29,15)+*; 2-graph
Sage cannot build a (842  435  224  225 ) that exists. Comment from Brouwer's database: S(2,15,421)?; 2-graph
Sage cannot build a (891  90   9    9   ) that exists. Comment from Brouwer's database: GQ(10,8)
Sage cannot build a (891  800  718  720 ) that exists. Comment from Brouwer's database:
Sage cannot build a (899  448  222  224 ) that exists. Comment from Brouwer's database: pg(28,15,14)?; 2-graph*
Sage cannot build a (899  450  225  225 ) that exists. Comment from Brouwer's database: S(2,15,435)?; 2-graph*
Sage cannot build a (900  435  210  210 ) that exists. Comment from Brouwer's database: OA(30,15)?; RSHCD<sup>+</sup>; 2-graph
Sage cannot build a (900  464  238  240 ) that exists. Comment from Brouwer's database: OA(30,16)?; 2-graph
Sage cannot build a (936  375  150  150 ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#JankoKharaghani02">Janko-Kharaghani</a>; pg(25,14,10)?
Sage cannot build a (936  560  334  336 ) that exists. Comment from Brouwer's database:
Sage cannot build a (957  256  80   64  ) that exists. Comment from Brouwer's database: S(2,8,232)
Sage cannot build a (957  700  507  525 ) that exists. Comment from Brouwer's database: pg(28,24,21)
Sage cannot build a (962  465  224  225 ) that exists. Comment from Brouwer's database: switch OA(31,16)+*; switch skewhad<sup>2</sup>+*; 2-graph
Sage cannot build a (962  496  255  256 ) that exists. Comment from Brouwer's database: S(2,16,481)?; 2-graph
Sage cannot build a (975  462  205  231 ) that exists. Comment from Brouwer's database: pg(14,32,7)?; 2-graph*
Sage cannot build a (975  512  280  256 ) that exists. Comment from Brouwer's database: 2-graph*
Sage cannot build a (976  480  248  224 ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (976  495  238  264 ) that exists. Comment from Brouwer's database: Goethals-Seidel(5,15); pg(15,32,8)?; 2-graph
Sage cannot build a (1024 231  38   56  ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Polhill09">Polhill</a>; possibly projective 4-ary [77,5] code with weights 56, 64
Sage cannot build a (1024 264  56   72  ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Polhill09">Polhill</a>; pg(11,23,3)?; possibly projective 4-ary [88,5] code with weights 64, 72
Sage cannot build a (1024 297  76   90  ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Polhill09">Polhill</a>; possibly projective 4-ary [99,5] code with weights 72, 80
Sage cannot build a (1024 330  98   110 ) that exists. Comment from Brouwer's database: <a href="srgtabrefs.html#Polhill08">Polhill</a>; pg(15,21,5)?; possibly projective 4-ary [110,5] code with weights 80, 88
Sage cannot build a (1024 693  472  462 ) that exists. Comment from Brouwer's database:
Sage cannot build a (1024 726  518  506 ) that exists. Comment from Brouwer's database:
Sage cannot build a (1024 759  566  552 ) that exists. Comment from Brouwer's database:
Sage cannot build a (1024 792  616  600 ) that exists. Comment from Brouwer's database:
Sage cannot build a (1080 351  126  108 ) that exists. Comment from Brouwer's database: NO<sup>+</sup>(4,3)
Sage cannot build a (1080 728  484  504 ) that exists. Comment from Brouwer's database: pg(26,27,18) - Mathon
Sage cannot build a (1105 80   15   5   ) that exists. Comment from Brouwer's database: U(4,4) polar graph; GQ(16,4)
Sage cannot build a (1105 1024 948  960 ) that exists. Comment from Brouwer's database:
Sage cannot build a (1107 378  117  135 ) that exists. Comment from Brouwer's database: NO<sup></sup>(8,3)
Sage cannot build a (1107 728  484  468 ) that exists. Comment from Brouwer's database:
Sage cannot build a (1176 300  54   84  ) that exists. Comment from Brouwer's database: NO<sup></sup>(5,7)
Sage cannot build a (1176 875  658  630 ) that exists. Comment from Brouwer's database:
Sage cannot build a (1215 574  253  287 ) that exists. Comment from Brouwer's database: pg(14,40,7)?; 2-graph*
Sage cannot build a (1215 640  352  320 ) that exists. Comment from Brouwer's database: 2-graph*
Sage cannot build a (1216 600  312  280 ) that exists. Comment from Brouwer's database: 2-graph
Sage cannot build a (1216 615  294  328 ) that exists. Comment from Brouwer's database: Goethals-Seidel(6,15); pg(15,40,8)?; 2-graph
Sage cannot build a (1225 384  138  112 ) that exists. Comment from Brouwer's database: NO<sup>+</sup>(5,7)
Sage cannot build a (1225 578  273  272 ) that exists. Comment from Brouwer's database: OA(35,17)?; Pasechnik(35)
Sage cannot build a (1225 612  305  306 ) that exists. Comment from Brouwer's database: skewhad$^2$; OA(35,18)?; 2-graph*
Sage cannot build a (1225 646  339  342 ) that exists. Comment from Brouwer's database: OA(35,19)?
Sage cannot build a (1225 840  567  595 ) that exists. Comment from Brouwer's database: pg(24,34,17)?
Sage cannot build a (1226 595  288  289 ) that exists. Comment from Brouwer's database: switch skewhad<sup>2</sup>+*; 2-graph
Sage cannot build a (1226 630  323  324 ) that exists. Comment from Brouwer's database: S(2,18,613)?; 2-graph
Sage cannot build a (1288 495  206  180 ) that exists. Comment from Brouwer's database:
Sage cannot build a (1288 792  476  504 ) that exists. Comment from Brouwer's database: M<sub>24</sub> / 2.M<sub>12</sub>; pairs of dodecads; pg(22,35,14)?
Sage cannot build a (1295 646  321  323 ) that exists. Comment from Brouwer's database: pg(34,18,17)?; 2-graph*
Sage cannot build a (1295 648  324  324 ) that exists. Comment from Brouwer's database: S(2,18,630)?; 2-graph*
Sage cannot build a (1296 629  304  306 ) that exists. Comment from Brouwer's database: RSHCD<sup></sup>; 2-graph
Sage cannot build a (1296 630  306  306 ) that exists. Comment from Brouwer's database: OA(36,18)?; RSHCD<sup>+</sup>; 2-graph
Sage cannot build a (1296 665  340  342 ) that exists. Comment from Brouwer's database: OA(36,19)?; Goethals-Seidel(2,35); 2-graph
Sage cannot build a (1296 666  342  342 ) that exists. Comment from Brouwer's database: 2-graph
<BLANKLINE>
In Andries Brouwer's database:
- 448 impossible entries
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1 of   3 in sage.graphs.strongly_regular_db._check_database

[94 tests, 1 failure, 43.92 s]
sage -t --long src/sage/groups/perm_gps/permutation_groups_catalog.py


### comment:34 Changed 5 years ago by ncohen

Why exactly are you seting this ticket to needs_work ? All tests pass on my machine.

### comment:35 in reply to: ↑ 33 Changed 5 years ago by ncohen

With #18988, #18960, and #18948:

Both #18988 and #18960 depend on #18948.

Nathann

### comment:36 Changed 5 years ago by ncohen

• Status changed from needs_work to positive_review

### comment:37 Changed 5 years ago by vbraun

• Status changed from positive_review to needs_work

Yes so if its not this ticket then its one of the dependencies. I'll leave it to you to figure out which of your tickets breaks the test.

### comment:38 Changed 5 years ago by ncohen

This ticket has only one dependency, i.e. #18934. You must be confused.

### comment:39 Changed 5 years ago by vbraun

The dependency is fine. But when I merge this ticket and then #18988 and #18960 on top of this ticket then tests fail.

### comment:40 Changed 5 years ago by ncohen

I don't know what exactly you are doing, but unless there is something wrong with this branch as it is, please set it back to positive_review.

### comment:41 Changed 5 years ago by ncohen

By the way, all 'merge' operations that you may perform between those three tickets should result in a 'fast-forward', as they are all linearly ordered.

### comment:42 follow-up: ↓ 43 Changed 5 years ago by vbraun

There is something wrong with this branch, it doctests implementation details instead of mathematical truths. Hence it is so fragile that even you yourself can't avoid breaking it. You can take care of the problem here or in a subsequent ticket, I don't care which.

### comment:43 in reply to: ↑ 42 Changed 5 years ago by ncohen

There is something wrong with this branch, it doctests implementation details instead of mathematical truths.

Wow. I could remove 50% of Sage's doctests with a rule like that.

Hence it is so fragile that even you yourself can't avoid breaking it. You can take care of the problem here or in a subsequent ticket, I don't care which.

Excellent. Then if you agree that rewriting the dependencies of 3 stacked tickets is a bad idea, then I chose to do it later.

The doctest counts the number of graphs that we are not able to build automatically. These doctests are very precious, and there are many like that in the combinat.design folder already. It is admittedly a mess during the early stages of the implementation, especially when you forget (as I did) to order everything linearly from the beginning.

When tickets will start getting merged it will become easier. Here my trouble today was with #18934, which is "not in a release beta" but "already closed". If not for that, I would have moved it atop of the others, and there would have been no work involved.

Nathann

### comment:44 Changed 5 years ago by ncohen

Dima? Unless you can tell me what you request to be changed on this ticket, please set it back to its original status.

### comment:45 follow-up: ↓ 47 Changed 5 years ago by vbraun

Well as long as you are only hurting yourself good luck with that. Of course you could alternatively run your own doctests before having #18988 reviewed, that would also avoid test failures.

Just set this ticket back to positive review once you have fixed #18988 or wherever you want to address it.

### Changed 5 years ago by dimpase

top part of git log

### comment:46 follow-up: ↓ 48 Changed 5 years ago by dimpase

I have very similar failure if I test with --long. The relevant part of the git log is attached.

### comment:47 in reply to: ↑ 45 Changed 5 years ago by ncohen

Of course you could alternatively run your own doctests before having #18988 reviewed, that would also avoid test failures.

Scuse me, can you show me this 'doctest failure' you mention? I do not see it. I load the branch, I run the tests, they pass. Something different happens on your computer?

Just set this ticket back to positive review once you have fixed #18988 or wherever you want to address it.

Tell me what you want to see fixed, and I will. If there is nothing to fix here, please change the status.

Nathann

### comment:48 in reply to: ↑ 46 ; follow-up: ↓ 52 Changed 5 years ago by ncohen

I have very similar failure if I test with --long. The relevant part of the git log is attached.

Then the answer is in your git log: there are commits from #18972 in your history, which have nothing to do there.

Nathann

### comment:49 Changed 5 years ago by vbraun

I want fixed that: #18988 + #18960 + #18948 together shall pass doctests.

### comment:50 follow-up: ↓ 53 Changed 5 years ago by ncohen

They do. Have you found a proof of the contrary? You do not even have to merge them, they are linearly ordered already.

### comment:51 Changed 5 years ago by ncohen

Unless you want also me to magically make them pass doctests with a non-reviewed ticket #18972, as Dima seems to expect?

### comment:52 in reply to: ↑ 48 ; follow-up: ↓ 54 Changed 5 years ago by dimpase

I have very similar failure if I test with --long. The relevant part of the git log is attached.

Then the answer is in your git log: there are commits from #18972 in your history, which have nothing to do there.

These commits should not affect the outcome, or at least I don't see how they can. Or, if you like, I have weird test failures on my branch due to something in your already reviewed tickets...

### comment:53 in reply to: ↑ 50 ; follow-up: ↓ 55 Changed 5 years ago by vbraun

They do. Have you found a proof of the contrary?

Yes, comment:33

### comment:54 in reply to: ↑ 52 ; follow-up: ↓ 57 Changed 5 years ago by ncohen

These commits should not affect the outcome, or at least I don't see how they can.

Easy: you add constructions of strongly regular graphs. The only thing this doctest does is check the *COUNT* of them (note that the individual lines naming each graph are not check, except the first, because of '...'). Given that you add constructions, the final number changes, and the doctest breaks.

Or, if you like, I have weird test failures on my branch due to something in your already reviewed tickets...

Just load *ONLY* the branch, and you will not have any problem. If you add other commits, now, I can do no magic.

Nathann

### comment:55 in reply to: ↑ 53 Changed 5 years ago by ncohen

Yes, comment:33

If you read his 'history' file you will see that he tested more commits than that. He also had some commits of hiw own patch (#18972) in his history. If you load only the branch on my tickets things work, but you can't expect me to fix in my branches the errors introduced on non-reviewed tickets. The only thing that it proves is that #18972 needs to be rebased on #18988. And that's clearly not my job.

Nathann

### comment:56 follow-up: ↓ 59 Changed 5 years ago by vbraun

comment:33 is from the buildbot and does not include any non-reviewed tickets:

### comment:57 in reply to: ↑ 54 ; follow-up: ↓ 58 Changed 5 years ago by dimpase

These commits should not affect the outcome, or at least I don't see how they can.

Easy: you add constructions of strongly regular graphs. The only thing this doctest does is check the *COUNT* of them (note that the individual lines naming each graph are not check, except the first, because of '...'). Given that you add constructions, the final number changes, and the doctest breaks.

Oh hell... How about we add a special tag (say, countexamples) to these counting test(s), so that they don't normally run.

Or, if you like, I have weird test failures on my branch due to something in your already reviewed tickets...

Just load *ONLY* the branch, and you will not have any problem. If you add other commits, now, I can do no magic.

The problem is that nobody expects the Spanish Inquisition hitting on your tests this way. Doctesting such counts is akin to doctesting number of Sage tests that pass...

### comment:58 in reply to: ↑ 57 ; follow-up: ↓ 63 Changed 5 years ago by ncohen

The problem is that nobody expects the Spanish Inquisition hitting on your tests this way. Doctesting such counts is akin to doctesting number of Sage tests that pass...

Regardless of that, the doctests pass, in this ticket and in those above.

Nathann

### comment:59 in reply to: ↑ 56 Changed 5 years ago by ncohen

comment:33 is from the buildbot and does not include any non-reviewed tickets:

Is this buildbot running beta0 (which does *not* include #18934) or is it running your own more-updated relase (which includes #18934)?

Last edited 5 years ago by ncohen (previous) (diff)

### comment:60 follow-up: ↓ 61 Changed 5 years ago by vbraun

The buildbot always merges dependencies first; Currently I'm at

d3a0be9 Trac #18989: Incorrect input_alphabet in FiniteStateMachine.disjoint_union
00f8736 Trac #18938: Refactor shortest paths
387fe06 Trac #17462: Remove the (deprecated) _boundary parameter
d868995 Trac #18608: Arc method in BalancedIncompleteBlockDesign class
649bf59 Trac #18585: Comparison of sparse polynomials
d9bb5de Trac #18978: gf2x fails to build with GCC 5.2
3c97405 Trac #18775: polytopes.icosidodecahedron and graphs.TruncatedIcosidodecahedralGraph
af59a3f Trac #18977: ncurses fails to build with GCC 5.2
4f379dc Trac #18860: Faster Poyhedron.graph()
47f6780 Trac #18975: make searches case-insensitive by default
50f503f Trac #18976: Update to IPython 3.2.1
8063cb3 Trac #18961: upgrade  ECL to 15.3.7
d6a3379 Trac #18934: New (v,6,1)-BIBD with v<=201
82513eb Trac #18089: Automaton.shannon_parry_markov_chain: New method
01a74d6 Trac #10194: Set factories
3b7932c Trac #18963: Remove 5 occurrences of FSMOldProcessOutput (Followup to #16133)
9559da6 Trac #18967: Silence the messages about deleting empty directories
0247d96 Trac #18742: interactive_simplex_method: Support several styles corresponding to major textbooks
571ad54 Trac #18910: Boost minimum spanning tree
c33a40b Trac #18876: Boost Cuthill-McKee, King Ordering
02125c0 Trac #18557: Implement FiniteStateMachine.disjoint_union (and .__or__)
f4a0ac6 Trac #18556: FiniteStateMachine.is_deterministic: machines with >1 initial states are non-deterministic
c0d4e06 Trac #18282: Fixes, cleanup and improvements to the default evaluation method for univariate polynomials
b74bb0b Trac #12607: ChainComplex reports zero homology groups (depending on ChomP)
d401fff Trac #18831: Hyperelliptic point counting various methods disagree
edb1b08 Updated Sage version to 6.9.beta0


### comment:61 in reply to: ↑ 60 Changed 5 years ago by ncohen

The buildbot always merges dependencies first; Currently I'm at

So that is your explanation. Yesterday, or that night, you ran the doctests on a version of Sage which included #18934. This branch, at that time, did not have #18934 as a dependency. This morning, I rebased this ticket (and those above) over #18934, and I fixed it. So now it should work, because of this rebasing. So unless you find something wrong with this branch, please set it back to its original status.

Nathann

### comment:62 follow-up: ↓ 64 Changed 5 years ago by vbraun

And this is why it shouldn't be possible to change positively reviewed branches... we can implement a cool-off period just for you if you prefer ;-)

### comment:63 in reply to: ↑ 58 ; follow-up: ↓ 65 Changed 5 years ago by dimpase

As the reviewer, I hereby humbly beg for the _check_database() test to be amended; either suppress checking the actual numbers by ..., or give it an extra optional tag so that it does not stand in the way.

### comment:64 in reply to: ↑ 62 Changed 5 years ago by ncohen

And this is why it shouldn't be possible to change positively reviewed branches... we can implement a cool-off period just for you if you prefer ;-)

Create a poll on sage-devel.

### comment:65 in reply to: ↑ 63 ; follow-up: ↓ 66 Changed 5 years ago by ncohen

As the reviewer, I hereby humbly beg for the _check_database() test to be amended; either suppress checking the actual numbers by ..., or give it an extra optional tag so that it does not stand in the way.

If we do it now, I will have to re-merge 3 linearly ordered patches again. So let's do that later.

Nathann

### comment:66 in reply to: ↑ 65 Changed 5 years ago by dimpase

As the reviewer, I hereby humbly beg for the _check_database() test to be amended; either suppress checking the actual numbers by ...`, or give it an extra optional tag so that it does not stand in the way.

If we do it now, I will have to re-merge 3 linearly ordered patches again. So let's do that later.

Can you do this on #18988, or whatever ticket that has the latest commits in this chain?

### comment:67 Changed 5 years ago by ncohen

Yeah yeah. I'm against it, but after having been complaining pointlessly for 30 minutes on a ticket because you were all testing something different from the branch stored on this ticket, I won't even bother trying to explain.

Nathann

Last edited 5 years ago by ncohen (previous) (diff)

### comment:68 Changed 5 years ago by ncohen

Easier to blame the doctest, of course.

### comment:69 follow-up: ↓ 73 Changed 5 years ago by ncohen

Let's create another ticket for that. It's unrelated to the topic of #18988..

### comment:70 Changed 5 years ago by ncohen

So? Are you now convinced that there is no broken doctest in this ticket, and that it can be set back to its original status ?

### comment:71 follow-up: ↓ 72 Changed 5 years ago by vbraun

• Status changed from needs_work to positive_review

I'm not necessarily convinced but I can try again... hopefully I'll get through a testing cycle before the branch changes again ;-)

### comment:72 in reply to: ↑ 71 Changed 5 years ago by ncohen

I'm not necessarily convinced but I can try again... hopefully I'll get through a testing cycle before the branch changes again ;-)

Yeah, sorry for that. I should have remembered to keep such tickets in a linear order at all times.