#11523: Implementation of Cohen-Macaulay test for simplicial complexes
----------------------------------------------------------+-----------------
Reporter: stumpc5 | Owner:
malb
Type: enhancement | Status:
new
Priority: major | Milestone:
sage-4.7.2
Component: commutative algebra | Keywords:
Cohen-Macaulay, homology, simplicial complexes
Work_issues: further improvement of _enlarge_subcomplex | Upstream:
N/A
Reviewer: | Author:
Christian Stump
Merged: | Dependencies:
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Comment(by jhpalmieri):
I'm sorry, I forgot about this ticket.
Overall, I think this looks pretty good. Some comments and questions:
- I had to rebase this against 4.7.2.alpha2.
- why have both `is_cohen_macaulay` and `is_cohen_macaulay_parallel`?
When would you ever want to use the first one? With ncpus=1, the parallel
one is about as fast as the first, so should we get rid of the first one?
- on the other hand, when I run the parallel version with ncpus=1, I
sometimes see an error:
{{{
Exception OSError: (10, 'No child processes') in <generator object
__call__ at 0x10d20ee10> ignored
}}}
and then the computation proceeds. Should we try to catch this and hide
it? Can we do that if it says "ignored"?
- in my testing
(`timeit('simplicial_complexes.NotIConnectedGraphs(5,2).homology()')`), I
saw no change in the time required to do homology computations from the
old version to the new one, but if you have other ideas for speeding
things up, please implement them.
- the method `face_iterator` has no documentation.
I don't know if this was ready for review, but I'm attaching a new version
of the patch which makes some of these changes: it renames
`is_cohen_macaulay` to `_is_cohen_macaulay_serial` (so it's hidden),
renames the parallel version to `is_cohen_macaulay`. I wonder if we
should set ncpus to be 2 by default instead of 1? I'll try testing on a
machine with just one cpu to see what effect that has.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11523#comment:3>
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