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Intersections and saturations of FreeQuadraticModules have the wrong ambient module #24702

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simonbrandhorst opened this issue Feb 10, 2018 · 9 comments
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Intersections and saturations of FreeQuadraticModules have the wrong ambient module #24702

simonbrandhorst opened this issue Feb 10, 2018 · 9 comments
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c: linear algebra p: critical / 2 t: bug
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sage-8.2

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@simonbrandhorst
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sage: L = FreeQuadraticModule(ZZ,2,matrix.identity(2))
sage: S1 = L.submodule([(1,0)])
sage: S2 = L.submodule([(0,1)])
sage: S1.intersection(S2).ambient_module()
Ambient free module of rank 2 over the principal ideal domain Integer Ring

Thus the intersection changes the ambient module. And in particular the inner product. This breaks other things like fgp modules too.

The same holds for saturations.

CC: @sagetrac-pmenegat

Component: linear algebra

Author: Simon Brandhorst

Branch/Commit: 0dd7769

Reviewer: David Roe

Issue created by migration from https://trac.sagemath.org/ticket/24702
@simonbrandhorst simonbrandhorst added this to the sage-8.2 milestone Feb 10, 2018
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Branch: u/sbrandhorst/intersections_of_freequadraticmodules_have_the_wrong_ambient_module

@simonbrandhorst
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Changed branch from u/sbrandhorst/intersections_of_freequadraticmodules_have_the_wrong_ambient_module to none

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@simonbrandhorst simonbrandhorst changed the title Intersections of FreeQuadraticModules have the wrong ambient module Intersections and saturations of FreeQuadraticModules have the wrong ambient module Feb 10, 2018
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Branch: u/sbrandhorst/intersections_of_freequadraticmodules_have_the_wrong_ambient_module

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sagetrac-git mannequin commented Feb 10, 2018

Branch pushed to git repo; I updated commit sha1. New commits:

0dd7769Indentation

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sagetrac-git mannequin commented Feb 10, 2018

Commit: 0dd7769

@roed314
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roed314 commented Feb 21, 2018

comment:7

Looks good to me. Patchbot failures seem spurious.

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roed314 commented Feb 21, 2018

Reviewer: David Roe

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vbraun commented Feb 22, 2018

Changed branch from u/sbrandhorst/intersections_of_freequadraticmodules_have_the_wrong_ambient_module to 0dd7769

@vbraun vbraun closed this as completed in 7640d68 Feb 22, 2018
This was referenced Nov 1, 2020
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@sagetrac-pmenegat sagetrac-pmenegat mannequin mentioned this issue May 8, 2018
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