#17053: Add function for direct sum of posets
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Reporter: jmantysalo | Owner:
Type: enhancement | Status: new
Priority: major | Milestone: sage-wishlist
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by ncohen):
Hello !
> Function could then be something like
1) Besides checking that `other` is a !Poset, I do not understand why this
function should do anything else than calling the graph routine. And it
would be that routine's job to check that the input is correct.
2) I believe that the default behaviour should be "pairs", because it is
the behaviour that keeps the most information. And people can force
`relabel="integers"` if they like.
> 1) Why I must say `other.hasse_diagram()` on last line,
`other._hasse_diagram` should work. Again some copy-immutable -thing?
Because of that:
{{{
sage: Poset(DiGraph({"a":["b"]})).hasse_diagram().vertices()
['a', 'b']
sage: Poset(DiGraph({"a":["b"]}))._hasse_diagram.vertices()
[0, 1]
}}}
> 2) What should be the name of parameter and values for it?
`verbose_relabel` to be consistent with graphs? Default value for it?
I don't really know... `verbose_relabel` in the !Graph function is not a
very good name, so perhaps we should change it. What about
`Poset.relabel(labels="pairs")` by default, and `labels="integers"`
otherwise ? And we could update the graph function with it. That also
involves deprecating the old parameter name.
Nathann
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Ticket URL: <http://trac.sagemath.org/ticket/17053#comment:7>
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