#16597: Singer difference set and fix OA_9_135
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Reporter: vdelecroix | Owner:
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-6.3
Component: combinatorial | Resolution:
designs | Merged in:
Keywords: | Reviewers:
Authors: Vincent Delecroix | Work issues:
Report Upstream: N/A | Commit:
Branch: | ec6df26f4d72c5eb939a9b02cd3ad809feacb105
u/vdelecroix/16597 | Stopgaps:
Dependencies: |
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Comment (by ncohen):
> I will put it back if you prefer. I just remarked that I removed an
important comment about PG2 being the set of points = 0 mod 39.
Your commit does not seem to remove any comment `O_o`
> But note that it is faster to test "x%39 == 0" rather than building PG2
and then test "x in PG2".
I know I know, but for such functions I gladly exchange a clear code
against a speedup. Which I expect is not so bad...
You can remove this PG2 if you want but then you must change the
explanation accordingly !
> No, `GF(q)` is not a number but a field. It refers to line as line in a
vector space over `GF(q)`. The very same way you would speak about `RR`
lines in `CC`. Isn't that clear enough?
Oh. I never said "RR lines in CC", but I get it know. I expected to see
the number of lines there.
Given that the base field is `GF(q)` just talking about lines is clear
enough though, isn't it ? You can leave it like that if you want, I am not
used to talk of "RR lines in CC", that's all.
> It is stupid.
Now try to think : you don't have to USE `is_cyclic` in your function. You
have the base block, i.e. `GF(q)-0` in `GF(q^3)-0`, and you can define the
automorphism on `GF(q^3)-0` with your generator. You don't have to build
the projective plane nor to compute its group, BUT you can use theorem
3.16 exactly as it is done in the book, by providing the base block and a
cyclic action on the ground set. 3.16 just does a relabelling.
Nathann
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Ticket URL: <http://trac.sagemath.org/ticket/16597#comment:6>
Sage <http://www.sagemath.org>
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