#16553: Clean IncidenceStructure
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Reporter: vdelecroix | Owner:
Type: enhancement | Status: needs_info
Priority: major | Milestone: sage-6.3
Component: combinatorial | Resolution:
designs | Merged in:
Keywords: | Reviewers:
Authors: Nathann Cohen, | Work issues:
Vincent Delecroix | Commit:
Report Upstream: N/A | a5c4dbc9d1b77315d90dd3dd7a8ccea780f59ecf
Branch: public/16553 | Stopgaps:
Dependencies: |
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Comment (by vdelecroix):
Replying to [comment:23 ncohen]:
> > Why not? It is well defined as soon as `t` is assumed to be smaller
than the block size. Note that if you have a t-(v,k,lambda) design it is
also a s-(v,k,lambda_s) design with
> > {{{
> > lambda_s = lambda binomial(v-s,t-s) / binomial(k-s,t-s).
> > }}}
> > (Handbook theorem II.4.8)
> >
> > I think that we should forbid lambda=0, that's all.
>
> Hmmmmmm... Makes total sense, sorry `O_o`
And actually:
- a design whose blocks have all the same lenght is a 0-design
- a 0-design for which each point has the same degree is a 1-design
I should modify the function to take care of that...
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Ticket URL: <http://trac.sagemath.org/ticket/16553#comment:28>
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