Minimal associated primes

[HechtiDerLachs]

An attempt to make the specialized functionality in Singular for zero dimensional ideals available.

This seemed to be useful for @simonbrandhorst in some examples, but now I can't even get the tests to terminate. Let's see what the CI says.

@wdecker : The documentation reads as if only QQ was allowed as a coefficient ring. Do you remember whether this is the case? Because it seems to have run also over number fields.

[HechtiDerLachs]

@ederc : Could you have a look at the tests? I don't understand what's going wrong. But maybe minimal_primes now called singular_generators before and that lead to some false caching?

[simonbrandhorst]

Thanks for wrapping this @HechtiDerLachs !

[ederc]

Well, the tests fail because you try to apply assPrimes from Singular on a zero dimensional ideal over a finite field, but assPrimes assumes that the ideal lives over QQ. AFAIK there is a modular std call behind the scenes in assPrimes.

[HechtiDerLachs]

The problem I meant occured in an earlier test run. Some call to dim was complaining that singular_groebner_generators did not return a groebner basis. But it doesn't seem to be reproduced anymore; sorry for calling you.

But what you say about minAss is good to know. I will restrict the cases where it's called.

[HechtiDerLachs]

@ederc : Now the error is back, see this test.

[ederc]

There was a missing caching of the isGB flag if a GB was computed during small_generating_set. I pushed a fix to your branch.

[simonbrandhorst]

is there anything holding this PR up @HechtiDerLachs ?

[HechtiDerLachs]

The tests were still failing. I just had a look and it seems there is another bug in minimal_primes (due to me, unfortunately). I will have a look.

[HechtiDerLachs]

@ederc : I'm sorry, but it looks like I accidentally overwrote your fixes to this branch when doing a rebase. Do you still have them somewhere? If yes, could you push them here again? Thx!

[ederc]

I do not have this code anymore, we need to look again where the isGB flag needs to be set.

[benlorenz]

@ederc : I'm sorry, but it looks like I accidentally overwrote your fixes to this branch when doing a rebase. Do you still have them somewhere? If yes, could you push them here again? Thx!

The Github UI shows HechtiDerLachs force-pushed the minimal_associated_primes branch from 9aa5177 to 2cd696e, and clicking on that 9aa5177 commit should get you to the last commit before the force push, and the history is also available. With that commit hash known you can also try doing git log 9aa5177 locally since git will keep lost commits for a few days.
You could also look through git reflog locally.

[ederc]

@HechtiDerLachs Caching isGB is back in.

[HechtiDerLachs]

Thanks a lot @ederc and @benlorenz ! I was hoping that something like this was possible, but didn't know how.

Unfortunately it seems that a lot of tests time out. Or something else goes wrong which I do not fully understand, yet.

Edit: I checked two of the failing tests locally around the point where they were cancelled and they run just fine on my machine.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.84%. Comparing base (b932d44) to head (70905de).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3705      +/-   ##
==========================================
- Coverage   83.56%   79.84%   -3.73%     
==========================================
  Files         589      589              
  Lines       80814    80834      +20     
==========================================
- Hits        67530    64538    -2992     
- Misses      13284    16296    +3012     

Files	Coverage Δ
src/Rings/mpoly-ideals.jl	89.25% <100.00%> (-3.67%)	⬇️

... and 201 files with indirect coverage changes

[HechtiDerLachs]

I really can't make sense of the failing tests. Everything that I tried on my local machine about things where the CI gets stuck really goes through for me. And in some cases I can't even find the error messages.