OA(9,120)

[nathanncohen]

As the title says ! Another one of Julian R. Abel's tricks ;-)

This one was... Painful to implement :-P

Nathann

Depends on #16524

CC: @videlec @KPanComputes @brettpim

Component: combinatorial designs

Author: Nathann Cohen

Branch/Commit: 2bd16e0

Reviewer: Vincent Delecroix

Issue created by migration from https://trac.sagemath.org/ticket/16528

[nathanncohen]

Commit: a600340

[nathanncohen]

New commits:

a600340

trac #16528: OA(9,120)

[nathanncohen]

Branch: u/ncohen/16528

[sagetrac-git]

Changed commit from a600340 to 3487f09

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. Last 10 new commits:

e948cf6	trac #16423: Aligning the alignment
0a7d853	trac #16423: Broken doctests
b329351	trac #16499: Cheap speedup in the OA recursive constructions
a67c04f	trac #16500: New recursive constructions of Orthogonal Arrays
41c50d5	trac #16500: Simplified find_recursive_construction
e1992ce	trac #16500: doc + speedup
697dd0c	trac #16500: Typoes in the doc
71dad5d	trac #16503: q-x construction of Orthogonal Arrays
002ceee	trac #16524: OA(9,135)
3487f09	trac #16528: OA(9,120)

[videlec]

comment:3

Just comments about my commit (at u/vdelecroix/16528)

Why if it is precomputed you do the extra check

for B in BIBD:
    len_trace = sum(x in hyperoval for x in B)
    assert len_trace == 0 or len_trace == 2

(commented in my commit)

I replaced the ugly Matrix[x].dict().keys() by M.nonzero_positions_in_row(x).

In two places it is not needed to build a list, Python iterator are useful for that

- len_trace = len([x for x in B if x in hyperoval])
+ len_trace = sum(x in hyperoval for x in B)
-    r = {v:i for i,v in enumerate([x for x in range(n) if x not in hyperoval])}
+    r = {v:i for i,v in enumerate(x for x in range(n) if x not in hyperoval)}

That's all before the positive review.

Vincent

[nathanncohen]

Changed commit from 3487f09 to c80b7f4

[nathanncohen]

comment:4

Yo !

Why if it is precomputed you do the extra check

for B in BIBD:
    len_trace = sum(x in hyperoval for x in B)
    assert len_trace == 0 or len_trace == 2

(commented in my commit)

Because it costs nothing, and because, given that the constructions are not always obvious, it is good to explain what is happening all along. It works the same way if it is commented.

I replaced the ugly Matrix[x].dict().keys() by M.nonzero_positions_in_row(x).

Thanks ! I did not know this function before you used it in another ticket.

In two places it is not needed to build a list, Python iterator are useful for that

If you believe that it makes any difference ... :-P

That's all before the positive review.

Okayyyyyy ! Thanks, then :-)

Nathann

P.S. : Something weird is happening. That's the last construction in needs_review ! I will fix that as soon as I get Julian's next mail ;-)

Nathann

---

New commits:

c80b7f4

trac #16528: review

[nathanncohen]

Reviewer: Vincent Delecroix

[nathanncohen]

Changed branch from u/ncohen/16528 to u/vdelecroix/16528

[nathanncohen]

Changed branch from u/vdelecroix/16528 to u/ncohen/16528

[nathanncohen]

Changed commit from c80b7f4 to 2bd16e0

[nathanncohen]

New commits:

2bd16e0

trac #16528: Broken doctest

[vbraun]

Changed branch from u/ncohen/16528 to 2bd16e0