LatticePoset: "antidoubling", part 3

[jm58660]

This patch adds a function to recognize if a lattice can be constructed by Day doubling constructions of any (possible) subsets. (Also adds "interface" for #22693.) The code may be unoptimal. For those who want to think:

CC: @mantepse @tscrim

Component: combinatorics

Author: Jori Mäntysalo

Branch/Commit: 13abce1

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/22745

[jm58660]

Branch: u/jmantysalo/latticeposet___antidoubling___part_3

[jm58660]

comment:2

Ready for review.

---

New commits:

8c4a3df

Add more tests for being doubling constructible.

[jm58660]

Commit: 8c4a3df

[sagetrac-git]

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

48fb811

Merge branch 'develop' into t/22745/latticeposet___antidoubling___part_3

[sagetrac-git]

Changed commit from 8c4a3df to 48fb811

[jm58660]

comment:4

Martin? This is quite direct implementation.

Long note in the decription is not needed for review.

[sagetrac-git]

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

87d58c2

Add a test.

[sagetrac-git]

Changed commit from 48fb811 to 87d58c2

[jm58660]

comment:6

I got an answer from Tristan Holmes. There are lattices that have congruence lattice having both maximal chains satisfying and not satisfying the needed property. Hence the code can not be easily optimized.

(There is room for optimization -- not all congruences are always needed to compute -- but that's a different story.)

[sagetrac-git]

Changed commit from 87d58c2 to 74af0fe

[sagetrac-git]

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

74af0fe

Merge branch 'develop' into t/22745/latticeposet___antidoubling___part_3

[jm58660]

comment:8

Travis, can you look at this?

(I think that after this, maybe in July, I want to make a code for doing the decomposition. Not sure if it should be a certificate for this or another function. Anyways, congruence-related functions are almost done now.)

[tscrim]

comment:9

One little this:

-                if e_up not in reachable:
-                    if splitting_depth_2(e, e_up):
+                if e_up not in reachable and splitting_depth_2(e, e_up):

Otherwise LGTM.

[tscrim]

Reviewer: Travis Scrimshaw

[sagetrac-git]

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

13abce1

From if-if to if-and.

[sagetrac-git]

Changed commit from 74af0fe to 13abce1

[jm58660]

comment:11

If ...: ... if changed to if ... and ...:.

[tscrim]

comment:12

Thanks.

[vbraun]

Changed branch from u/jmantysalo/latticeposet___antidoubling___part_3 to 13abce1