#19078: Finite posets: Faster is_antichain_of_poset()
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Reporter: jmantysalo | Owner:
Type: defect | Status: new
Priority: minor | Milestone: sage-6.9
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: Jori Mäntysalo | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/jmantysalo/finite_posets__faster_is_antichain_of_poset__|
38400a3da6f9d4885f0b36cd2169cc5c14b0142c
Dependencies: | Stopgaps:
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Changes (by jmantysalo):
* commit: => 38400a3da6f9d4885f0b36cd2169cc5c14b0142c
Comment:
After `P = Posets.BooleanLattice(10); l = P.level_sets()[5]` this patch
reduced time for `P.is_antichain_of_poset(l)` from 642 ms to 558 ms. That
is 13% faster.
At the same time the index in `posets.py` can be slightly better, as now
both `is_chain_of_poset()` and `is_antichain_of_poset()` are defined in
the same file. Also the user will get error message always, if there is an
element of `elms` not in the poset.
The code may seem slightly odd, but AFAIK there is no built-in way in
Python to get pairs `(a,b)` from list `L` such that `L.index(a) <
L.index(b)`. This implementation was fastest I found.
However, I am waiting for #18941 to get accepted (or rejected). Then I'll
add this to index of functions. (Assuming that #19061 isn't done yet.)
----
New commits:
||[http://git.sagemath.org/sage.git/commit/?id=6bd3062abf58e9bb1db4cb5d4aced453c72edf5e
6bd3062]||{{{Added a function is_antichain_of_poset to posets.py.}}}||
||[http://git.sagemath.org/sage.git/commit/?id=38400a3da6f9d4885f0b36cd2169cc5c14b0142c
38400a3]||{{{Removed spaces from empty line.}}}||
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Ticket URL: <http://trac.sagemath.org/ticket/19078#comment:3>
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