#6102: cohomology ring of simplicial complexes
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Reporter: bantieau | Owner: bantieau
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.4
Component: algebraic | Resolution:
topology | Merged in:
Keywords: | Reviewers:
Authors: John Palmieri | Work issues:
Report Upstream: N/A | Commit:
Branch: u/jhpalmieri/AT- | 5923e23d857ecdda88cd84d8b70d0ea2228acbde
model | Stopgaps:
Dependencies: #19179 |
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Comment (by jhpalmieri):
An update: I have a new version of `algebraic_topological_model.py`, which
is the key to everything here. I'm calling it `AT_model.py`, and I'll
attach it to the ticket. The good news:
- it works for Delta complexes
- it's faster with mod 2 coefficients:
{{{
sage: from sage.homology.algebraic_topological_model import
algebraic_topological_model
sage: from sage.homology.AT_model import AT_model
sage: RP3 = simplicial_complexes.RealProjectiveSpace(3)
sage: %time phi, H = algebraic_topological_model(RP3, GF(2)) # old version
CPU times: user 813 ms, sys: 150 ms, total: 963 ms
Wall time: 852 ms
sage: %time phi, H = AT_model(RP3, GF(2)) # new version
CPU times: user 345 ms, sys: 32.3 ms, total: 377 ms
Wall time: 354 ms
}}}
The bad news: it's ''much'' slower with rational coefficients, and I have
no idea why:
{{{
sage: %time phi, H = algebraic_topological_model(RP3, QQ) # old version
CPU times: user 1.27 s, sys: 138 ms, total: 1.41 s
Wall time: 1.35 s
sage: %time phi, H = AT_model(RP3, QQ) # new version
CPU times: user 23.9 s, sys: 69.6 ms, total: 24 s
Wall time: 24 s
}}}
Profiling the code with `%prun` was not illuminating to me, and I couldn't
run `%crun` because I couldn't get
[https://github.com/gperftools/gperftools the Google performance analysis
tools] to install on my machine. Optimizing code is not my strong suit, in
any case.
Because of this, I haven't tried to implement cup products for Delta
complexes. I think I know how to do that, but it hasn't felt worth it yet.
--
Ticket URL: <http://trac.sagemath.org/ticket/6102#comment:17>
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