#20078: Minimal non faces of simplicial complexes: Improve speed
-------------------------------------+-------------------------------------
Reporter: jipilab | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-7.1
Component: algebraic | Resolution:
topology | Merged in:
Keywords: simplicial | Reviewers:
complex, minimal nonface | Work issues:
Authors: Jean-Philippe | Commit:
Labbé | a26ad0bfff0273656cebb060691056dd75fc2f7b
Report Upstream: N/A | Stopgaps:
Branch: |
u/jipilab/minnonface |
Dependencies: |
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Description changed by jipilab:
Old description:
> The current implementation to compute minimal non-faces of simplicial
> complexes is really slow:
>
> {{{
> sage: SC = SimplicialComplex([(0,1,2),
> (0,2,3),
> (2,3,4),
> (1,2,4),
> (1,4,5),
> (0,3,6),
> (3,6,7),
> (4,5,7)])
> sage: %time SC.minimal_nonfaces()
> CPU times: user 11 s, sys: 140 ms, total: 11.2 s
> Wall time: 11.2 s
> {(3, 4, 7), (5, 6), (0, 4), (0, 5), (3, 5), (4, 6), (2, 5), (0, 7), (1,
> 3), (1, 7), (1, 6), (2, 6), (2, 7)}
> }}}
>
> This is a difficult problem but it seems that the algorithm could be
> improved with not too much efforts. I made a first try here:
>
> {{{
> sage: %time mnf(SC)
> CPU times: user 21.3 ms, sys: 4.25 ms, total: 25.6 ms
> Wall time: 26.6 ms
> {{3, 4, 7}, {0, 7}, {0, 4}, {0, 5}, {3, 5}, {1, 7}, {2, 5}, {5, 6}, {1,
> 3}, {4, 6}, {1, 6}, {2, 6}, {2, 7}}
> }}}
New description:
The current implementation to compute minimal non-faces of simplicial
complexes is really slow:
{{{
sage: SC = SimplicialComplex([(0,1,2),
(0,2,3),
(2,3,4),
(1,2,4),
(1,4,5),
(0,3,6),
(3,6,7),
(4,5,7)])
sage: %time SC.minimal_nonfaces()
CPU times: user 11 s, sys: 140 ms, total: 11.2 s
Wall time: 11.2 s
{(3, 4, 7), (5, 6), (0, 4), (0, 5), (3, 5), (4, 6), (2, 5), (0, 7), (1,
3), (1, 7), (1, 6), (2, 6), (2, 7)}
}}}
This is a difficult problem in general, but it seems that the algorithm
could be improved with not too much efforts. I made a first try here:
{{{
sage: %time SC.minimal_nonfaces()
CPU times: user 14 ms, sys: 12.4 ms, total: 26.4 ms
Wall time: 30.5 ms
{(3, 4, 7), (0, 7), (0, 4), (0, 5), (3, 5), (1, 7), (2, 5), (5, 6), (1,
3), (4, 6), (1, 6), (2, 6), (2, 7)}
}}}
--
--
Ticket URL: <http://trac.sagemath.org/ticket/20078#comment:11>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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