[seqfan] Re: CROSSREFS

[Olivier Gerard]

On Sat, Oct 23, 2010 at 00:12, Vladimir Orlovsky <4vladimir at gmail.com>wrote:

> Hello Seqfans,
>
> I have quostion about `Crossrefs`.
> So far, it's done very badly|incomplete.
>
>
So far, it is done mainly manually starting from the handbook of integer
sequences
in the 1970s. Except for the two lines "Sequences in context" and "Adjacent
sequences"
which are generated automatically.


> For example: seq `A` can have `Cf. B`, but seq `B` has NO
> reference|relation
> for seq 'A'.
>
>
This is often on purpose if B is a very important sequence, a "core"
sequence.
Many sequences are related to B but it is important to select only of the
few of
the one that are referenced from B.
The classic example is the integers. The Bell numbers and the Fibonacci
numbers
also come to mind.  A simple search with the OEIS is more efficient in these
cases
than crossreferencing hundreds of sequences.


> One life example:
> id:A144229  CROSSREFS:  Cf. A076725
> id:A076725  CROSSREFS  Cf. A000283, A112969, A114793.
> Adjacent sequences: A076722 A076723 A076724 this_sequence A076726 A076727
> A076728
> Sequence in context: A175172 A126469 A054859 this_sequence A059917 A093625
> A042447

My quostion(s):
> is it OK?
>

It should be appreciated individually. Crossrefs are mainly here to point
out non-evident relationships or to make links between sequences that have
been created as a series
or as a couple. They should be mainly dedicated to distance 1 relationships.
If not
you end up putting the whole OEIS graph in the crossref line.


> is it concern to any one?
>

It is the concern of many seqfans to discover and document relations between
sequences.
It is also an important part of mathematics to show relations between
objects.


> is any one working in this area? ....etc
>
>
Yes, and the wiki version of the OEIS will improve the way we deal with
cross-references.

In the meantime if you want to contribute and improve the OEIS, please
submit a comment
for the relevant sequences indicating the sequence reference and the nature
of the relationship.


Thanks,
> Vladimir Orlovsky
>
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