#18023: Add methods for shelling orders
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Reporter: fcastillo | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.6
Component: combinatorics | Resolution:
Keywords: simplicial | Merged in:
complex, shellable | Reviewers: Travis Scrimshaw
Authors: Federico | Work issues:
Castillo, Travis Scrimshaw | Commit:
Report Upstream: N/A | b4f8282e8ac7695d9ed8bca2a97f19a6a7275eae
Branch: | Stopgaps:
public/combinat/shelling_order-18023|
Dependencies: |
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Old description:
> We add methods to check if a given order of facets is a shelling order
> and for calculating restricted sets (when shellable). We add some code
> in a doctest for a specialized method for computing the ''h'' vector,
> which should get merged into a class for `ShellableComplexes` (when such
> a class gets created).
New description:
We add methods to check if a given order of facets is a shelling order and
for calculating restricted sets (when shellable). This also adds code to
construct the f-triangle and h-triangles (to use for basic tests for
shellability). We add some code in a doctest for a specialized method for
computing the ''h'' vector, which should get merged into a class for
`ShellableComplexes` (when such a class gets created).
--
Comment (by tscrim):
Good points. I've made some minor tweaks so that this works for non-pure
complexes as well. I've added the f/h triangles and do shortcuts for
shellability testing. I've also rewritten the algorithm for `is_shellable`
to do backtracing in following the link you posted. I'll also run some
more tests with Federico (next week when I get back to Davis).
--
Ticket URL: <http://trac.sagemath.org/ticket/18023#comment:6>
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