#16391: Helper functions for OA constructions
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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/16391 | 2090875de8a5d9a0301a85fc35e0e60a068de1ab
Dependencies: #16370 | Stopgaps:
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Comment (by vdelecroix):
Hi Nathann,
I switch to this one from #16361 because of the comment I wrote there. But
in the function `OA_with_holes` implemented in the branch associated to
that ticket, you do strictly the same thing. You rely heavily on the
output of `designs.orthogonal_array(k,n)` whose specifications are :
"Returns '''an''' orthogonal array with parameters (k,n)". It is neither
intended to be constant over time (and you do not want to impose that) and
it is not optimized with respect to any property. One reason is that we
want to shortcut as possible the recursive constructions which are time
consuming. If someone comes with a nice one parameter family of `OA(k, k^2
+ 3*k + 19)` we would use that first whatever it breaks elsewhere.
You can not reasonably force the implementation of
`designs.orthogonal_array` to output something optimal with respect to the
property you are interested in today. It might really be that tomorrow,
you would prefer to have a `designs.orthogonal_array` with very few
multiplicity of `TD(k,1)` in it.
Right now, we have several constructions of OA with the same parameters
(for example, several Wilson construction might be available). The
multiplicity of `TD(k,1)` you obtain must strongly depend on the way you
did your construction and '''we do not want''' that
`designs.orthogonal_array` takes this strategy.
Vincent
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Ticket URL: <http://trac.sagemath.org/ticket/16391#comment:6>
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