#16985: Poset: Faster is_selfdual()
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Reporter: jmantysalo | Owner:
Type: enhancement | Status: new
Priority: minor | Milestone: sage-wishlist
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/jmantysalo/poset__faster_is_dual__|
ef4707bad72ee6a544a816092aed84e6b988fb87
Dependencies: | Stopgaps:
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Comment (by jmantysalo):
Replying to [comment:10 ncohen]:
> > Hmm, actually it seems that only `reverse()` is needed. There is no
need at all to calculate full dual with element labels. Got to think about
this tomorrow.
>
> {{{
> sage: Poset(DiGraph({0:[],1:[2]})).level_sets()
> [[1, 0], [2]]
> sage: Poset(DiGraph({0:[],1:[2]})).dual().level_sets()
> [[0, 2], [1]]
> }}}
I don't understand. Of course we must sometimes do full test for
isomorphicity. This is one example of those.
Saying `Poset({'a':['b']})._hasse_diagram.level_sets()` will return `[[0],
[1]]`, not `[['a'], ['b']]`. But in any case, code seems to reverse an
array, which is unneeded.
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Ticket URL: <http://trac.sagemath.org/ticket/16985#comment:11>
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