[Opt-Mucca]

Description

See #3478 for a full description of the issue. Essentially: If we drop terms with small coefficients from the LP aggregation without considering their domains then we run the risk of generating invalid cuts. We already made changes along this line for conflict analysis a month or so ago.

This change affects 1/3 instances and at least on my test set is 1% performance negative. I'd say this is a necessary evil, but it still sucks. Interestingly, after the change I am solving more instances and getting more consistent speed-ups than slow-downs across seeds, so this is a nice change for future benchmarking. The big losers that drag down the average seem to be problems with large column domains, where two instances in particular get consistently 2-4x slower. @fwesselm I'm happy for this to wait for further testing.

Checklist

• I have read the contributing guidelines
• This PR targets the latest branch
• Tests are passing
• Documentation was updated where relevant
• This PR is not primarily AI-generated (per the AI contributions policy in CONTRIBUTING.md)

Related issue

Closes #3478

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.50%. Comparing base (78d8f09) to head (45815a8).
⚠️ Report is 10 commits behind head on latest.

Additional details and impacted files

@@            Coverage Diff             @@
##           latest    #3507      +/-   ##
==========================================
+ Coverage   75.46%   75.50%   +0.03%     
==========================================
  Files         461      461              
  Lines      113232   113254      +22     
  Branches    17881    17883       +2     
==========================================
+ Hits        85456    85514      +58     
+ Misses      27488    27452      -36     
  Partials      288      288              

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[fwesselm]

Looks good, @Opt-Mucca!

Could termIsZero live in util/HighsUtils.h maybe? I think its usage will grow... :)

[jajhall]

Could termIsZero live in util/HighsUtils.h maybe? I think its usage will grow... :)

It seems a bit closely tied to HighsDomain, but if you want it, then please make the change so that this can be merged

[fwesselm]

Could termIsZero live in util/HighsUtils.h maybe? I think its usage will grow... :)

It seems a bit closely tied to HighsDomain, but if you want it, then please make the change so that this can be merged

@jajhall @Opt-Mucca: I moved the function and added a test.

[Opt-Mucca]

@fwesselm you beat me to it! Luckily I had just started working on it, so no time wasted. (Been sidetracked by some presolve stuff all day)

I like it living in HighsUtil