Opened 5 years ago

Closed 5 years ago

#19360 closed enhancement (fixed)

Poset documentation polishing: comparing & intervals

Reported by: jmantysalo Owned by:
Priority: minor Milestone: sage-6.10
Component: documentation Keywords:
Cc: kdilks Merged in:
Authors: Jori Mäntysalo Reviewers: Kevin Dilks
Report Upstream: N/A Work issues:
Branch: f406e5e (Commits) Commit: f406e5e86e7f37ed9693e6ad6860de43020dbbc9
Dependencies: Stopgaps:

Description

Check documentation of functions like is_less_than().

This continues the serie of #18925, #18941, #18959 and #19141.

Change History (12)

comment:1 Changed 5 years ago by jmantysalo

  • Cc kdilks added

Kevin, what you think about "Relations are also often called intervals."? I would say that every comparable element pair defines an interval, not that it is an interval. Actually the name of intervals()/relations() could be comparable_pairs(), or even not-yet-implemented chains(size=2). But maybe that would go too far.

But should we deprecate intervals, as it does not return intervals but a pairs of elements?

comment:2 Changed 5 years ago by kdilks

I thought I responded to this, but maybe this was the response I had typed out just after my free 30 minute wifi session at O'Hare expired...

I don't think relations are often (or ever) called intervals. So deprecate that, but maybe add a docstring comment to relations() indicating that the number of relations is the number of intervals, and is thus the dimension of the incidence algebra.

Not especially a fan of comparable_pairs(), just because technically speaking pairs are unordered, and we care about the order of the pair. I also don't think chains(size=2) would be a good option, either.

The way that I think of posets (and the way the poset constructor thinks of them) is that you have data of a ground set and relations, and how all of that data interacts makes a poset structure. Things like chains and intervals are properties of the entire poset structure, whereas relations are an individual piece of the defining data.

comment:3 Changed 5 years ago by jmantysalo

  • Branch set to u/jmantysalo/poset_documentation_polishing__comparing___intervals

comment:4 Changed 5 years ago by git

  • Commit set to 9dcc412a4416aa7b8fad962b1d0f974f7460922a

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

9dcc412A typo in the index.

comment:5 Changed 5 years ago by jmantysalo

What should I do to interval? Now it is de facto alias to closed_interval (or to other way), but technically a function.

comment:6 Changed 5 years ago by git

  • Commit changed from 9dcc412a4416aa7b8fad962b1d0f974f7460922a to aea0eff7c7f5bce8ebf9d218a0df6c2c0575bd0a

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

aea0effMore polishing to docstrings.

comment:7 Changed 5 years ago by jmantysalo

  • Status changed from new to needs_review

I guess this can be reviewed as it is.

Different question is that should open_interval(x, y) and open_interval(y, x) return just same elements.

comment:8 Changed 5 years ago by git

  • Commit changed from aea0eff7c7f5bce8ebf9d218a0df6c2c0575bd0a to 3cc556da45d5540a3cfb7536777102548ba5edca

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

3cc556dChange one .intervals() to .relations().

comment:9 Changed 5 years ago by git

  • Commit changed from 3cc556da45d5540a3cfb7536777102548ba5edca to f406e5e86e7f37ed9693e6ad6860de43020dbbc9

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

f406e5eResolved a conflict with new beta.

comment:10 Changed 5 years ago by kdilks

  • Reviewers set to Kevin Dilks
  • Status changed from needs_review to positive_review

I don't think open_interval(x,y) and open_interval(y,x) should always return the same thing.

Looks good.

comment:11 Changed 5 years ago by jmantysalo

Thank you! Now this is starting to look quite good.

comment:12 Changed 5 years ago by vbraun

  • Branch changed from u/jmantysalo/poset_documentation_polishing__comparing___intervals to f406e5e86e7f37ed9693e6ad6860de43020dbbc9
  • Resolution set to fixed
  • Status changed from positive_review to closed
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