Regular partitions: 1-regular partitions are mishandled on occasion

[darijgr]

1-regular partitions exist (although there is just one of them -- the empty one). Not all of the code behaves well at \ell=1, though; e.g., the iterator runs infinite loops once it's past [].

CC: @tscrim

Component: combinatorics

Keywords: partition, regular partition, border case

Author: Travis Scrimshaw

Branch/Commit: 7ba506c

Reviewer: Darij Grinberg

Issue created by migration from https://trac.sagemath.org/ticket/20584

[tscrim]

Branch: public/combinat/fix_1_regular_partitions-20584

[tscrim]

Commit: 2f0f912

[tscrim]

comment:1

Hey, I finally remembered to fix this. ^^;;

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New commits:

2f0f912

Better handle 1-regular partitions.

[tscrim]

Author: Travis Scrimshaw

[sagetrac-git]

Changed commit from 2f0f912 to 7ba506c

[sagetrac-git]

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

9fb5274	Merge branch 'public/combinat/fix_1_regular_partitions-20584' of git://trac.sagemath.org/sage into reg
7ba506c	minor corrections

[darijgr]

comment:4

Fixed a couple little things, one of which predated this ticket.

I don't know if there is an established way of guaranteeing that any function/method that takes a regular partition will still work with a 1-regular partition. Barring that, the only criterion are the doctests, right? Everything else LGTM.

[tscrim]

comment:5

Replying to @darijgr:

Fixed a couple little things, one of which predated this ticket.

Thanks.

I don't know if there is an established way of guaranteeing that any function/method that takes a regular partition will still work with a 1-regular partition. Barring that, the only criterion are the doctests, right? Everything else LGTM.

No, I don't think there is such a way other than those functions/methods having explicit checks. This is a degenerate case in terms of my applications (there is not really an [affine] sl₁), so I'm not really worried.

[tscrim]

Reviewer: Travis Scrimshaw

[tscrim]

Changed reviewer from Travis Scrimshaw to Darij Grinberg

[vbraun]

Changed branch from public/combinat/fix_1_regular_partitions-20584 to 7ba506c