Opened 5 months ago

Closed 5 months ago

Last modified 4 months ago

#16678 closed defect (fixed)

Fix coercions for descent and symmetric group algebras

Reported by: tscrim Owned by: tscrim
Priority: major Milestone: sage-6.3
Component: coercion Keywords: symmetric group algebra, descent algebra
Cc: darij Merged in:
Authors: Travis Scrimshaw Reviewers: Darij Grinberg
Report Upstream: N/A Work issues:
Branch: d8ea764 (Commits) Commit:
Dependencies: Stopgaps:

Description (last modified by tscrim)

This splits off the first issue of #15475 (which has already been reviewed by Darij). This will also address the issues noted on https://groups.google.com/forum/#!topic/sage-devel/rXobHQXrCck.

Change History (12)

comment:1 Changed 5 months ago by tscrim

  • Branch set to public/coercion/fix_sga_coercions-16678
  • Commit set to e1ff76939b42bd0c0bd20af1ea365b5b7f1aa5f8
  • Description modified (diff)
  • Status changed from new to needs_review

Last 10 new commits:

7637ab2Implemented _coerce_map_from_ for SGA.
0763ba5More fixes and doctests.
db24a90Fixed the issue...finally... Also some other minor cleanup.
fb8c9c9Added comment about register_embedding.
702e7a1Changed to use _coerce_map_from_ and made it more robust/general.
f662ae3documentation fixes to canonical_embedding of symmetric group algebra (yes, these maps aren't always embeddings, and the inequality was backwards)
ff4e546oops, another doc fix
b3d98baMerge commit 'ff4e546a838e9e9a4be86b3a89d8596658beb3f4' into public/coercions/fix_sga_coercions-16678
31c8ac9Additional fixes noted on sage-devel thread.
e1ff769Fixed stupid mistake.

comment:2 Changed 5 months ago by git

  • Commit changed from e1ff76939b42bd0c0bd20af1ea365b5b7f1aa5f8 to 30e769e05e76d19b2057c7bb1f32a3f1f80c72f4

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

30e769eRemoved erroneous character in permgroup.py.

comment:3 Changed 5 months ago by git

  • Commit changed from 30e769e05e76d19b2057c7bb1f32a3f1f80c72f4 to 3fa802d270a0d6f560ecd845132c22a85add33ee

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

3fa802da couple doctests and a blunder of my own

comment:4 Changed 5 months ago by darij

Thanks for the split, which was rather appropriate. Positive_review on my side.

comment:5 Changed 5 months ago by tscrim

  • Status changed from needs_review to positive_review

Thanks Darij.

comment:6 Changed 5 months ago by vbraun

  • Status changed from positive_review to needs_work
sage -t --long src/sage/categories/groups.py
**********************************************************************
File "src/sage/categories/groups.py", line 531, in sage.categories.groups.Groups.Algebras.example
Failed example:
    GroupAlgebras(QQ).example(SymmetricGroup(4))
Expected:
    Group algebra of Symmetric group of order 4! as a permutation group over Rational Field
Got:
    Symmetric group algebra of order 4 over Rational Field
**********************************************************************
File "src/sage/categories/groups.py", line 578, in sage.categories.groups.Groups.Algebras.ParentMethods.algebra_generators
Failed example:
    GroupAlgebras(QQ).example(SymmetricGroup(10)).algebra_generators()
Expected:
    Finite family {(1,2): B[(1,2)], (1,2,3,4,5,6,7,8,9,10): B[(1,2,3,4,5,6,7,8,9,10)]}
Got:
    [[2, 1, 3, 4, 5, 6, 7, 8, 9, 10], [2, 3, 4, 5, 6, 7, 8, 9, 10, 1]]
**********************************************************************
sage -t --long src/sage/combinat/root_system/hecke_algebra_representation.py
**********************************************************************
File "src/sage/combinat/root_system/hecke_algebra_representation.py", line 81, in sage.combinat.root_system.hecke_algebra_representation.HeckeAlgebraRepresentation.__init__
Failed example:
    HeckeAlgebraRepresentation(domain, action, CartanType(["A",2]), 1, -1)
Expected:
    A representation of the (1, -1)-Hecke algebra of type ['A', 2]
    on Group algebra of Symmetric group of order 3! as a permutation group over Rational Field
Got:
    A representation of the (1, -1)-Hecke algebra of type ['A', 2] on Symmetric group algebra of order 3 over Rational Field
**********************************************************************
File "src/sage/combinat/root_system/hecke_algebra_representation.py", line 229, in sage.combinat.root_system.hecke_algebra_representation.HeckeAlgebraRepresentation.on_basis
Failed example:
    rho.on_basis(W.one(), (1,2,1))
Expected:
    B[(1,3)]
Got:
    (1,3)
**********************************************************************

comment:7 Changed 5 months ago by git

  • Commit changed from 3fa802d270a0d6f560ecd845132c22a85add33ee to d8ea76401d64a798f3d1d6cf7a0d7e0dbdd7c099

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

500735dMerge branch 'public/coercion/fix_sga_coercions-16678' of trac.sagemath.org:sage into public/coercion/fix_sga_coercions-16678
d8ea764Fixed trivial doctest failures.

comment:8 Changed 5 months ago by tscrim

  • Status changed from needs_work to positive_review

Trivial failures due to SGA's being returned from SymmetricGroup(n).algebra().

comment:9 Changed 5 months ago by vbraun

  • Branch changed from public/coercion/fix_sga_coercions-16678 to d8ea76401d64a798f3d1d6cf7a0d7e0dbdd7c099
  • Resolution set to fixed
  • Status changed from positive_review to closed

comment:10 Changed 4 months ago by nthiery

  • Commit d8ea76401d64a798f3d1d6cf7a0d7e0dbdd7c099 deleted

See followup #16625. Sorry I did not spot this earlier; it's too bad the change was released in 6.3, since now we are reverting a backward incompatible change, making it compabible back to <=6.2 but not 6.3 ...

comment:11 follow-up: Changed 4 months ago by darij

#16925, not #16625.

I'm seeing it right that only the SymmetricGroup?.Algebra part of this ticket will be reverted?

comment:12 in reply to: ↑ 11 Changed 4 months ago by nthiery

Replying to darij:

#16925, not #16625.

Oops, I am up-down dislexic apparently :-)

I'm seeing it right that only the SymmetricGroup?.Algebra part of this ticket will be reverted?

Definitely.

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