#18529: Topological manifolds: basics
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Reporter: egourgoulhon | Owner: egourgoulhon
Type: enhancement | Status: needs_info
Priority: major | Milestone: sage-7.0
Component: geometry | Resolution:
Keywords: topological | Merged in:
manifolds | Reviewers: Travis Scrimshaw
Authors: Eric Gourgoulhon, | Work issues:
Travis Scrimshaw | Commit:
Report Upstream: N/A | c38ae80cbd8032cf7041259284b6f646265d1e42
Branch: | Stopgaps:
public/manifolds/top_manif_basics |
Dependencies: #18175 |
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Comment (by egourgoulhon):
Replying to [comment:99 tscrim]:
> Then how about we have a `_distinguished_open_cover`, which is set to
the first open cover that gets added?
Well the tensor field `__eq__` mentionned above is only one of the
possible examples where open covers could be involved. One may imagine
that they are also used in tensor field `_add_` for instance. This is not
the case at the moment, but this is certainly something to be considered
when discussing the tensor field arithmetics.
So, at this stage, I would prefer a sequence (i.e. a Python list) of open
covers instead of a set with a distinguished element. IMO, this offers a
greater flexibility for future operations, like `_add_`. With a sequence,
you may always say that your distinguished element is the first one, and
if, for some reason, the attempted operation fails with it, you may try
with the second one, and so on (while if you have only a distinguished
element, you don't know what to do in case of failure).
So could we stay with a list at this stage?
--
Ticket URL: <http://trac.sagemath.org/ticket/18529#comment:100>
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