#15875: Add is_subposet
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Reporter: csar | Owner:
Type: enhancement | Status: needs_work
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 | 29ab8f2b3ba3fb8d6366f694c26866e1c0f3e4fe
Dependencies: | Stopgaps:
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Comment (by ncohen):
> This is not at all clear from the note-block
I cannot say that I agree with you, though there is a mistake in the note.
The first sentence should be changed to: "This method does not check
whether the poset is *isomorphic* to a subposet of ``other``, but only if
[...]".
> (and the `is_subgraph` and "induced" in graph theory might carry a
slightly different meaning than I'm used to when looking at posets)
The meaning is the same. Though this function should *not* check by
default that it is an *induced* subposet. It should check whether it is a
subposet, e.g.: the antichain is a subposet of any poset with the same
elements.
Futhermore:
{{{
sage: A = posets.ChainPoset(5)
sage: A.is_subposet(A)
False
}}}
Nathann
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Ticket URL: <http://trac.sagemath.org/ticket/15875#comment:24>
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