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oscar-system / Oscar.jl

A comprehensive open source computer algebra system for computations in algebra, geometry, and number theory.
https://www.oscar-system.org
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Basic geometry code still needed? #1651

Closed HereAround closed 6 months ago

HereAround commented 1 year ago

src/geometry/basics.jl contains basic definitions for (weighted) projective spaces. We have this and more with toric geometry (once https://github.com/oscar-system/Oscar.jl/pull/1646 is merged). @fieker (unless I am mistaken you worked most on this file) I wonder if this code is then still needed? If yes, we should document it.

fingolfin commented 1 year ago

The code in question now lives in src/AlgebraicGeometry/Miscellaneous/basics.jl and indeed was written by @fieker, IIRC in order to support the code in experimental/PlaneCurve/.

I think it has a different range of supported cases (e.g. it can be used over Z/nZ).

We discussed this before: there are many different "models" of projective spaces (as varieties, manifolds, incidence geometries, combinatorial objects, etc.), so it is unlikely we'll ever get away with a single universal one.

The main question then is how to make the different implementations available. A function like projective_space should probably allow to select the implementation, but also have a default...

As it is, I don't think there is need to remove this code, and also we would loose some functionality...

fingolfin commented 1 year ago

See also the past discussion in issue #922

joschmitt commented 6 months ago

The file was removed in #3179.