#16503: q-x construction of Orthogonal Arrays
-------------------------------------+-------------------------------------
Reporter: ncohen | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.3
Component: combinatorial | Resolution:
designs | Merged in:
Keywords: | Reviewers:
Authors: Nathann Cohen | Work issues:
Report Upstream: N/A | Commit:
Branch: u/ncohen/16503 | 71dad5d46b3fe7b343962974a75a9c199e0904a6
Dependencies: #16500 | Stopgaps:
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Comment (by vdelecroix):
Hi Nathann,
1) One lines 656-659 you have an import followed by a commented check!!
{{{
from sage.combinat.designs.bibd import _check_pbd
PBD = [[relabel[xx] for xx in B if not xx in points_to_delete] for B in
TD]
# _check_pbd(PBD,n,[q,q-x-1,q-x+1,x+2])
}}}
why is that?
2) This is wrong (lines 730-731)
{{{
# The next is always True, because q is a prime power
# orthogonal_array(k+1,q,existence=True) and
}}}
if k+1 > q... instead we can start the loop at k+1 instead of 3.
3) I bounced into something bad: I wanted to change in
`find_recursive_construction` the
{{{
assert k >= 3
}}}
into a
{{{
assert k > 3, "you do not need recursion for k<4"
}}}
since it is trivial to build one latin square. But it appears that the
recursive constructions is called with k=3 many times! so bad! This has to
be corrected... but hopefully, not here. I guess that #16535 would be the
good place.
Vincent
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Ticket URL: <http://trac.sagemath.org/ticket/16503#comment:6>
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