[seqfan] Re: intersection patterns of n sets
Joerg Arndt
arndt at jjj.de
Sun Dec 21 12:16:05 CET 2014
* Neil Sloane <njasloane at gmail.com> [Dec 21. 2014 09:49]:
> With 2 sets, they are disjoint, or one contains the other, or they have
> a nontrivial intersection, which is three ways, and 3 is not
> a term of A000088.
>
> So I don't understand your remark.
>
> Perhaps you were thinking the sets could also be equal?
Yes, of course!
> But that
> does not seem fair.
I do not understand why that should be bad:
A <==> B is something I'd very much like to allow.
But I realize that I did not think it through:
a set not connected to any other would be forced
to be connected to that "extra set".
Anyway, I speculate this is one of the old "core" seqs.
> If you start with three sets, then they are all
> different
>
> Best regards
> Neil
>
> [...]
Best, jj
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