#21002: LatticePoset: certificates for non-semimodularity
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Reporter: jmantysalo | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-7.3
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: Jori Mäntysalo | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/jmantysalo/latticeposet__certificates_for_non__semi_modularity_and_non_distributivity|
10cb3ca6bcfb3d79793200b9f1def5be584a8e46
Dependencies: | Stopgaps:
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Changes (by jmantysalo):
* status: needs_info => needs_review
* cc: tscrim (added)
* milestone: sage-feature => sage-7.3
* commit: => 10cb3ca6bcfb3d79793200b9f1def5be584a8e46
Old description:
> Add a `certificate`-option to the functions checking if a lattice is
> semimodular, modular or distributive.
New description:
Add a `certificate`-option to the functions checking if a lattice is
semimodular.
--
Comment:
I thinked about this, and here is first part.
First, this is faster for almost all cases. But for small lattices with
already computed meet, join and rank function this is slower. However, the
speedup for, say, `BooleanLattice(10)` is big. With current code the time
to check semimodularity is 4,9 seconds for first time and 0,6 seconds for
second time. With this patch it drops to 0,1 seconds.
Second, this adds a `certificate`-option.
I thinked this, and I guess we should use this by-definition -certificate,
and later implement `isomoprhic_sublattices()`.
I will put this to needs_review and later try to do something similar to
`is_modular()` and `is_distributive()`.
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New commits:
||[https://git.sagemath.org/sage.git/commit?id=10cb3ca6bcfb3d79793200b9f1def5be584a8e46
10cb3ca]||{{{Modifications to semimodularity tests.}}}||
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Ticket URL: <https://trac.sagemath.org/ticket/21002#comment:3>
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