Opened 6 months ago

Last modified 3 months ago

#31771 new enhancement

Chart.subchart_poset, superchart_poset, Manifold.chart_poset

Reported by: mkoeppe Owned by:
Priority: major Milestone: sage-9.5
Component: manifolds Keywords:
Cc: egourgoulhon, gh-mjungmath Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: #31720 Stopgaps:

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Description

Families of charts on a manifold are quasiordered by set inclusion of domains, ignoring coord_string. Subqosets can be defined by filtering by coord_string; an optional argument of Manifold.chart_poset will do this.

As in #31736, the poset quotients by the equivalence relation, so its elements are finite families of charts that have the same domain.

Change History (8)

comment:1 Changed 6 months ago by mkoeppe

  • Dependencies set to #31720

comment:2 Changed 6 months ago by gh-mjungmath

Probably perfect substitute for the current display implementation of scalar fields.

comment:3 follow-up: Changed 6 months ago by gh-mjungmath

I think this quasi order is exactly what we need for presheaves.

Since the set of frames as well as of charts each constitute a presheaf, what if we wrap this up in #31703?

Besides, what do you mean with "Subqosets"?

comment:4 Changed 6 months ago by mkoeppe

qoset = quasi-ordered set

comment:5 Changed 6 months ago by gh-mjungmath

But when we take coord_string into account again, shouldn't this become a poset? So you mean subqosets that are actual posets, right?

comment:6 Changed 6 months ago by mkoeppe

Two subsets with a different name can turn out to be equal. If two restrictions of a chart are defined on these two subsets, then I think these will be distinct but equal elements of the qoset as well.

comment:7 in reply to: ↑ 3 Changed 6 months ago by mkoeppe

Replying to gh-mjungmath:

Since the set of frames as well as of charts each constitute a presheaf, what if we wrap this up in #31703?

Sure, that would work; perhaps you can expand that ticket's description a bit.

comment:8 Changed 3 months ago by mkoeppe

  • Milestone changed from sage-9.4 to sage-9.5
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