#17361: Poset: Add ordinal_product
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Reporter: | Owner:
jmantysalo | Status: new
Type: | Milestone: sage-wishlist
enhancement | Resolution:
Priority: major | Merged in:
Component: | Reviewers:
combinatorics | Work issues:
Keywords: poset | Commit:
Authors: | abeef07ddd88246d8564692ff57ff17f62c5eb3f
Frédéric Chapoton | Stopgaps:
Report Upstream: N/A |
Branch: |
u/chapoton/17361 |
Dependencies: |
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Comment (by ncohen):
Hello !
Well, first for the poset thing you can be MUCH more efficient. In
`Poset.ordinal_sum` you add only edges between the top elements of one and
the bottom elements of the other. Why don't you do that here too ?
(please, cache the top/bottom elements of each poset).
Also, {{{for s in self for s2 in self.lower_covers(s)}}} should probably
be {{{for s,s in cover_relations_iterator}}}.
For the graph code, it could be improved by replacing the calls to
`add_edge` by one call to `add_edges`. The difference is that `add_edge`
supports many kind of inputs (a pair, or two points, or three points) and
that `add_edge` checks it at every call (while `add_edges` does it once).
Nathann
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Ticket URL: <http://trac.sagemath.org/ticket/17361#comment:11>
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