#15161: Parent/Element relation for ChainComplex/Chain
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Reporter: vbraun | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.12
Component: algebraic | Resolution:
topology | Merged in:
Keywords: | Reviewers:
Authors: Volker Braun | Work issues:
Report Upstream: N/A | Commit:
Branch: | 7e075ed92f58f2c1cf03518e0facbf9ee48c8a78
u/vbraun/chain_complex_parents | Stopgaps:
Dependencies: |
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Comment (by vbraun):
Here, element = chain, i.e. an element of the direct sum of the `C_i`.
That is the most general notion of element, so it is the one that ought to
be implemented. The arrows in the ascii art are there to visualize the
relative position in the complex. And they are `\to` and not `\mapsto`
arrows... Do you have a better ascii art representation in mind?
Since it is useful to see the coordinate expression of a chain that is
supported only in a single degree (e.g. homology generators) they are
printed differently:
{{{
sage: D = ChainComplex({0: matrix(ZZ, 2, 2, [1,0,0,2])})
sage: D()
Trivial chain
sage: D({0:[2, 3]})
Chain(0:(2, 3))
sage: D({0:[2, 3], 1:[4, 5]})
Chain with 2 nonzero terms over Integer Ring
sage: z = D({1:[0,1]})
sage: z.is_boundary()
False
sage: (2*z).is_boundary()
True
}}}
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Ticket URL: <http://trac.sagemath.org/ticket/15161#comment:6>
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