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FacadeInclusionMorphism #34461

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mkoeppe opened this issue Aug 31, 2022 · 7 comments · May be fixed by #35030
Open

FacadeInclusionMorphism #34461

mkoeppe opened this issue Aug 31, 2022 · 7 comments · May be fixed by #35030
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c: categories p: major / 3 t: enhancement

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mkoeppe commented Aug 31, 2022

To discuss the notion of "set inclusion" in the presence of coercion, we need to be able to discover inclusion morphisms (= injective coercion morphisms).

One mechanism to model subsets is through facade sets. But the relation of facade parents to the parent that they are a facade to is not known to the coercion system.

By registering a FacadeInclusionMorphism as a coercion, we can make this relation discoverable.

sage: from sage.categories.pushout import pushout
sage: from sage.categories.morphism import FacadeInclusionMorphism
sage: S = Sets().Facade().example(); S
An example of facade set: the monoid of positive integers
sage: iota = FacadeInclusionMorphism(Hom(S, ZZ))
sage: iota.register_as_coercion()
sage: pushout(S, ZZ)
Integer Ring

CC: @tscrim

Component: categories

Author: Matthias Koeppe

Branch/Commit: u/mkoeppe/facadeinclusionmorphism @ 5db7f09

Issue created by migration from https://trac.sagemath.org/ticket/34461
@mkoeppe mkoeppe added this to the sage-9.7 milestone Aug 31, 2022
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mkoeppe commented Aug 31, 2022

Branch: u/mkoeppe/facadeinclusionmorphism

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mkoeppe commented Aug 31, 2022

New commits:

5db7f09src/sage/categories/morphism.pyx (FacadeInclusionMorphism): New

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mkoeppe commented Aug 31, 2022

Author: Matthias Koeppe

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mkoeppe commented Aug 31, 2022

Commit: 5db7f09

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@mkoeppe mkoeppe modified the milestones: sage-9.7, sage-9.8 Aug 31, 2022
@mkoeppe mkoeppe modified the milestones: sage-9.8, sage-9.9 Jan 7, 2023
@mkoeppe mkoeppe mentioned this issue Jan 7, 2023
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@tscrim tscrim mentioned this issue Sep 14, 2022
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mkoeppe commented Feb 8, 2023

PR #35030 replaces the attached branch.

@mkoeppe mkoeppe modified the milestones: sage-10.0, sage-10.1 Apr 30, 2023
@mkoeppe mkoeppe removed this from the sage-10.1 milestone Aug 7, 2023
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src/sage/categories/morphism.pyx (FacadeInclusionMorphism): New mkoeppe/sage
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