Opened 3 years ago

Closed 3 years ago

#21263 closed enhancement (fixed)

Poset: additions to is_eulerian()

Reported by: jmantysalo Owned by:
Priority: major Milestone: sage-7.4
Component: combinatorics Keywords:
Cc: Merged in:
Authors: Jori Mäntysalo Reviewers: Frédéric Chapoton
Report Upstream: N/A Work issues:
Branch: 8eb5cc3 (Commits) Commit: 8eb5cc3aba871a6481e77ac27e0428a39e09edd6
Dependencies: Stopgaps:

Description

This patch will 1) slightly speed up computing is_eulerian(), 2) make it possible to check if a poset is (only) k-eulerian for some integer k, 3) get a "certificate" of non-eulerianity, i.e. endpoints of a non-eulerian interval and 4) add star_product(). The last logically belongs to this IMO, as it is mostly used for generating a new Eulerian poset.

It is logically possible to define this for P and Q if P has top and Q has bottom. However, this implementation requires both to have both bottom and top. On the other hand this does not check if a poset is graded.

Change History (12)

comment:1 Changed 3 years ago by jmantysalo

  • Branch set to u/jmantysalo/k-eulerian

comment:2 Changed 3 years ago by jmantysalo

  • Commit set to b92aa699f4f8709ca37fcb587f3e5b4591f5a9f8
  • Status changed from new to needs_review

New commits:

b92aa69Add star_product etc.

comment:3 follow-up: Changed 3 years ago by chapoton

in star, missing doctests for the raise statements.

comment:4 Changed 3 years ago by git

  • Commit changed from b92aa699f4f8709ca37fcb587f3e5b4591f5a9f8 to 6ec10fd511e5935ae763db60b5bd587a44df51c5

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

6ec10fdAdd tests for input checking.

comment:5 in reply to: ↑ 3 Changed 3 years ago by jmantysalo

Replying to chapoton:

in star, missing doctests for the raise statements.

Those done.

comment:6 follow-up: Changed 3 years ago by chapoton

There are some "eulerian" that should take a capital.

Do you have a reference for testing only even ranks differences ?

comment:7 Changed 3 years ago by git

  • Commit changed from 6ec10fd511e5935ae763db60b5bd587a44df51c5 to 1e73455de646964b5f4a45ec46120712c7f543bd

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

1e73455Capital letter in 'eulerian'.

comment:8 in reply to: ↑ 6 Changed 3 years ago by jmantysalo

Replying to chapoton:

There are some "eulerian" that should take a capital.

Those corrected. I don't know if I should write "k-Eulerian" or "k-eulerian"; Volker said that english is not consistent on that.

Do you have a reference for testing only even ranks differences ?

For example EC in pages 453-454 exercise 174c indirectly says that. For a paper see abstract of http://www.ms.uky.edu/~jrge/Papers/k-Eulerian.pdf

comment:9 follow-up: Changed 3 years ago by chapoton

  • Reviewers set to Frédéric Chapoton

ok, looks good. Please add a reference to the Ehrenborg article, and then you can set to positive.

comment:10 Changed 3 years ago by git

  • Commit changed from 1e73455de646964b5f4a45ec46120712c7f543bd to 8eb5cc3aba871a6481e77ac27e0428a39e09edd6

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

8eb5cc3Added reference for optimization.

comment:11 in reply to: ↑ 9 Changed 3 years ago by jmantysalo

  • Status changed from needs_review to positive_review

Replying to chapoton:

ok, looks good. Please add a reference to the Ehrenborg article, and then you can set to positive.

Done that.

comment:12 Changed 3 years ago by vbraun

  • Branch changed from u/jmantysalo/k-eulerian to 8eb5cc3aba871a6481e77ac27e0428a39e09edd6
  • Resolution set to fixed
  • Status changed from positive_review to closed
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