#19801: LatticePosets: Add pseudocomplements
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Reporter: jmantysalo | Owner:
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-7.0
Component: combinatorics | Resolution:
Keywords: lattice | Merged in:
Authors: Jori Mäntysalo | Reviewers: Daniel Krenn
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/jmantysalo/pseudocomplement | aafb86c7212eeeea29e460adaabd6c7884007594
Dependencies: | Stopgaps:
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Changes (by dkrenn):
* status: needs_review => needs_work
* reviewer: => Daniel Krenn
Comment:
Replying to [comment:3 jmantysalo]:
> Daniel showed some signs of life, hence selected as a possible reviewer.
`:=)`.
I had a quick look; here are a first few comments:
1. Everywhere: I believe the term "maximal element" is wrong; it should be
"greatest element" (Wikipedia confirms this).
2. Link to [https://en.wikipedia.org/wiki/Pseudocomplement] in the doc.
3. `None` vs. raising an exception if pseudocomplement does not exist.
Although I prefer the exception variant; it seems that `None` seems to be
the design choice in the poset-files. Am I right? However, this should
definitely be documented in an OUTPUT-block; so include OUTPUT-blocks.
4. PEP8: IMHO it should be: `{0: [1, 2], 1: [3], 2: [4], 3: [4]}` (spaces
after `:`)
5. `None not in [H.pseudocomplement(e) for e in H]` is inefficient, since
the full list is created. You can use `all(H.pseudocomplement(e) is not
None for e in H)` instead.
--
Ticket URL: <http://trac.sagemath.org/ticket/19801#comment:4>
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