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free Pre-Lie algebras #15635

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fchapoton opened this issue Jan 5, 2014 · 63 comments
Closed

free Pre-Lie algebras #15635

fchapoton opened this issue Jan 5, 2014 · 63 comments

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@fchapoton
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one has shuffle algebras, one could have pre-Lie algebras, as soon as one has rooted trees (#11529)

Depends on #11529

CC: @sagetrac-sage-combinat @tscrim @darijgr

Component: combinatorics

Keywords: trees, prelie algebra

Author: Frédéric Chapoton

Branch/Commit: 6fa6d78

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/15635

@fchapoton fchapoton added this to the sage-6.1 milestone Jan 5, 2014
@fchapoton
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@fchapoton
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Dependencies: #11529

@sagetrac-vbraun-spam sagetrac-vbraun-spam mannequin modified the milestones: sage-6.1, sage-6.2 Jan 30, 2014
@sagetrac-vbraun-spam sagetrac-vbraun-spam mannequin modified the milestones: sage-6.2, sage-6.3 May 6, 2014
@fchapoton
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comment:5

First step, a git branch that does not look too bad.


New commits:

83ea133trac #15635 first rough tentative of free Pre-Lie algebras

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Branch: u/chapoton/15635

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Commit: 83ea133

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sagetrac-git mannequin commented Jun 8, 2014

Changed commit from 83ea133 to a8f683d

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sagetrac-git mannequin commented Jun 8, 2014

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

a8f683dtrac #15635 moving into combinat

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sagetrac-git mannequin commented Jun 9, 2014

Changed commit from a8f683d to aff5363

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sagetrac-git mannequin commented Jun 9, 2014

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

aff5363trac #15635 little cleanup

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sagetrac-git mannequin commented Jun 9, 2014

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

fe3a8a3trac #15635 two errors corrected

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sagetrac-git mannequin commented Jun 9, 2014

Changed commit from aff5363 to fe3a8a3

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sagetrac-git mannequin commented Jun 9, 2014

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

b7a7f57trac #15635 correction in shortcut notation <

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sagetrac-git mannequin commented Jun 9, 2014

Changed commit from fe3a8a3 to b7a7f57

@sagetrac-vbraun-spam sagetrac-vbraun-spam mannequin modified the milestones: sage-6.3, sage-6.4 Aug 10, 2014
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sagetrac-git mannequin commented Feb 16, 2015

Changed commit from b7a7f57 to 51eaee8

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sagetrac-git mannequin commented Feb 16, 2015

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

4e771e4Merge branch 'u/chapoton/15635' into 6.5.rc3
51eaee8trac #15635 a few details

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Changed keywords from trees to trees, prelie algebra

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Author: Frédéric Chapoton

@fchapoton
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comment:12

This should be ready, once rooted trees are ok.

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sagetrac-git mannequin commented Apr 29, 2015

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

db2e59eMerge branch 'u/chapoton/15635' into 6.7.b3
30f0ed6trac #15635 no more coerce_impl

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sagetrac-git mannequin commented Apr 29, 2015

Changed commit from f02c3af to 30f0ed6

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sagetrac-git mannequin commented May 1, 2015

Changed commit from 30f0ed6 to c42ba5a

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sagetrac-git mannequin commented May 1, 2015

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

c42ba5atrac #15635 removal of < shortcut, more doc

@fchapoton
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comment:29

Thanks Travis for your comments. I have done something for the first three, but I do not
understand the last one.

I removed the shortcut < alltogether. Using * is almost as good.

I removed coerced_impl and it still works.

I used len(self.algebra_generators()).

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tscrim commented May 1, 2015

comment:30

Thanks! The last one was that line was commented out with a line above it saying about Family not returning a consistent ordering, which is not correct as I understand it.

I plan to do a full review over this weekend.

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tscrim commented May 3, 2015

Reviewer: Travis Scrimshaw

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tscrim commented May 3, 2015

comment:31

I made some review changes:

  • I added algebras.FreePreLie and made this the standard entry point.
  • I moved the main explanation doc from the module level to the class. I also made some minor tweaks to the doc overall.
  • I also renamed the file by removing the s as this is the standard in Sage AFAIK.
  • I changed the output of algebra_generators as per my previous point. The ordering should be consistent as this was something we changed awhile ago.
  • Subsequently, I changed around some things so that it works with infinite generating sets.
  • I changed the some_elements and implemented an an_element method.

If you're happy with my changes, then you can set a positive review.

PS/EDIT - It would be nice to have the trees with specified labels, as this would allow the generic implementation of an_element and removing of the _alphabet parameter (well, pushing it down a level).


New commits:

da67955Reviewer changes to free pre-Lie algebras.
97c3312Changed the output of algebra_generators().
c833a23Adding support for infinite indexing sets.

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tscrim commented May 3, 2015

Changed work issues from coercion to none

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tscrim commented May 3, 2015

Changed branch from u/chapoton/15635 to u/tscrim/free_pre_lie-15635

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tscrim commented May 3, 2015

Changed commit from c42ba5a to c833a23

@fchapoton
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comment:32

Thanks a lot for your work on that ticket. I have not yet got time to look at your changes seriously.

  • I added algebras.FreePreLie and made this the standard entry point.

I do not quite agree. Most people would not call them algebras, because they are NOT associative

  • I moved the main explanation doc from the module level to the class. I also made some minor tweaks to the doc overall.
  • I also renamed the file by removing the s as this is the standard in Sage AFAIK.

No problem with removing s

  • I changed the output of algebra_generators as per my previous point. The ordering should be consistent as this was something we changed awhile ago.
  • Subsequently, I changed around some things so that it works with infinite generating sets.

Great !

  • I changed the some_elements and implemented an an_element method.

If you're happy with my changes, then you can set a positive review.

The first point is problematic in my opinion.

PS/EDIT - It would be nice to have the trees with specified labels, as this would allow the generic implementation of an_element and removing of the _alphabet parameter (well, pushing it down a level).

yes, I agree !

@fchapoton
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comment:33

Doc does not build, because of the removal of s was forgotten in module_list

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comment:34

corrected the module-list

there remains the problem about the entry in the catalog.


New commits:

616bacetrac #15635 fixing module list

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Changed commit from c833a23 to 616bace

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Changed branch from u/tscrim/free_pre_lie-15635 to public/ticket/15635

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sagetrac-git mannequin commented May 5, 2015

Changed commit from 616bace to 6fa6d78

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sagetrac-git mannequin commented May 5, 2015

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

6fa6d78trac #15635 another s forgotten

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tscrim commented May 6, 2015

comment:36

Thanks for fixing the module list (I didn't have time until this afternoon to come back to this).

Replying to @fchapoton:

  • I added algebras.FreePreLie and made this the standard entry point.

I do not quite agree. Most people would not call them algebras, because they are NOT associative

I understand your point, but what would people call them, non-associative algebras? The one of the current thoughts is to rename MagmaticAlgebras to Algebras and add axioms like "associative" (#15043). Also, what do you say about Jordan algebras being in the catalog?

Irregardless of nomenclature, I would say that having this as a global entry point doesn't harm anyone as the name is clear (and there's no danger of confusion), it is documented that it not associative, it makes it discoverable, and FreePreLieAlgebra in the global namespace IMO adds some clutter.

Another option would be to create a (stub) category for pre-Lie algebras, werhich might be bett for the long term, and have a method free similar to:

sage: Groups().free(names='x,y,z')
Free Group on generators {x, y, z}

(and something similar should probably be done for associative unital algebras).

@fchapoton
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comment:37
  • Jordan algebras are not in the catalog, as far as I can see (6.7.beta4)

  • if J is a Jordan algebra, then J in Algebras returns False

So I really think that the catalog 'algebras' should be kept for associative algebras.

Maybe this should be discussed on sage-devel or sage-combinat-devel ?

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tscrim commented May 6, 2015

comment:38

Replying to @fchapoton:

  • Jordan algebras are not in the catalog, as far as I can see (6.7.beta4)

I guess I forgot to add them...

  • if J is a Jordan algebra, then J in Algebras returns False

Hmm...this would definitely create an mild inconsistency in the current state with Algebras being associative and unital (at least in the global namespace; for imports, I would say the implementor should be aware of what assumptions are being made).

Maybe this should be discussed on sage-devel or sage-combinat-devel ?

This is now https://groups.google.com/forum/#!topic/sage-devel/uXN5619Fg54.

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tscrim commented May 9, 2015

comment:39

Given the discussion on sage-devel, would you be okay with letting this stay in the algebras catalog?

@fchapoton
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comment:40

Yes, ok to let it go in the algebra catalog.

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tscrim commented May 13, 2015

comment:41

Then positive review.

@vbraun
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vbraun commented May 13, 2015

Changed branch from public/ticket/15635 to 6fa6d78

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