#17173: Poset: faster is_distributive_lattice
-------------------------------------+-------------------------------------
Reporter: jmantysalo | Owner:
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-6.4
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: Jori Mäntysalo | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/jmantysalo/poset__faster_is_distributive_lattice|
d69e73a0a0a655e4e1595a77cda807ccb017fb02
Dependencies: | Stopgaps:
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Comment (by ncohen):
> I need the list.
Not there
{{{
len([e for e in self if len(self.lower_covers(e))==1])
}}}
nor there
{{{
if len(self.upper_covers(m))==1:
}}}
nor there
{{{
if len(M_.minimal_elements()) > 1:
}}}
> It starts with `x=give_an_array(y)` but if it's length is exactly one,
then continues with `z=x[0]`. Or do you mean optimizing it so that if code
founds out that `len(self.upper_covers(m)` is at least 2, it returns
False?
I have not read the algorithm closely yet, I do not know what it does
exactly. There are places in the code, however, where those lists are
created only to compute their length, e.g. above.
> Uh, I somehow thinked that it would be optimized out. But of course it
can not be done. I will correct this.
Python is the worst language ever. It is a script. I hate scripts.
> ?? I didn't touch it, just deprecated a function.
yes yes, but the deprecation breaks the tests. Run the tests and see ! It
is trivial, however, you probably only need to fix the output (which now
contains the deprecation warning).
> Thanks for comments! I'll continue with these later.
Good luck ! `:-)`
Nathann
--
Ticket URL: <http://trac.sagemath.org/ticket/17173#comment:6>
Sage <http://www.sagemath.org>
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