#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 | 08f4ad4c68c66484199c66a0fc20d02fd5bd0469
Dependencies: | Stopgaps:
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Comment (by jmantysalo):
The tests were succesfull, so I guess this can be reviewed, apart from the
naming issue:
Replying to [comment:51 ncohen]:
> What about naming it `.is_induced_subposet`? That would clear any doubt.
This is one possibility. I am just wondering about existing
`is_subgraph()` and planned `is_sublattice()`; naming convention should be
unified. Also this definition is logical in a sense that from
`Q=P.subposet(...whatever...)` you will always get `Q.is_subset(P)`
returning `True`.
The link
http://www.combinatorics.org/ojs/index.php/eljc/article/download/v16i1r142/pdf
seems to talk about isomorphic subposets.
Maybe we should write `.extensions()` and have `.is_weak_subposet()` be a
poset that is induced subposet of some extension? That is the terminology
used by ''Enumerative Combinatorics''. Also Macaulay2 uses `subposet` to
mean induced subposet.
Travis, comments? At least I must think over a night about this.
--
Ticket URL: <http://trac.sagemath.org/ticket/15875#comment:52>
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