#15875: Add is_subposet
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Reporter: csar | Owner:
Type: enhancement | Status: needs_info
Priority: major | Milestone: sage-6.9
Component: combinatorics | Resolution:
Keywords: posets | Merged in:
Authors: Jori Mäntysalo | Reviewers: Travis Scrimshaw
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/jmantysalo/is_subposet | c3b48f366eb7a82519338fb390d9363ce6c68180
Dependencies: | Stopgaps:
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Comment (by ncohen):
> tscrim: "we should have the subposet not depend on being a facade",
ncohen: "people want the elements to BELONG to this specific poset, and to
be different from anything that does not belong to the same poset" --> We
need a third opinion, I guess.
Ask on sage-devel. To me, what you are doing is this: the elements of a
non-facade poset have a different `.__eq__` method (which makes them
different when they belong to different posets), and by casting everything
to facade you say that you want to use the *normal* notion of equality.
That the only thing the non-facade posets are defined *for*: so that the
`.__eq__` of their elements has this property. If we workaround it, when
is it gonna stop? Are we suppoed to write non-facade-specific code in each
of the poset functions to avoid this senseless equality?
> Or should we raise something with facade posets?
To me it is very simple: do not write any non-facade-specific code, and
let them deal with the consequences of this poor design, without forcing
us to write additional code. On a personal level, if we have to deal with
this hell every time we work on posets, I do not plan to touch its code
again.
Nathann
--
Ticket URL: <http://trac.sagemath.org/ticket/15875#comment:48>
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