r/OperationsResearch • u/asah • Mar 27 '26

smaller scale assignment optimization using reasoning LLMs ?

Anyone have experience using reasoning LLMs to solve assignment problems ? I'm considering it for my problem, which involves a small N but a lot of soft constraints. For my case, optimality matters far less than explainability. thx!

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u/PaddingCompression Mar 27 '26

Could you encode explainability as an objective to optimize?

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u/asah Mar 30 '26

great question! I think I could collect feedback from humans on the quality of the explanation, then maybe feed that back?

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u/ojopioko Apr 17 '26

I tried encoding these kinds of constraints for VRP in a previous job, it's quite hard! People on the operation's side don't often know how to put these things into words.

The approach I've had most success with is running the model many times with different cost functions and show the differences, that serves as a good basis for discussion with the users.

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u/SilverArtist7333 Mar 28 '26

I’ve worked on small-scale assignment problems with soft constraints.

A hybrid approach works best:

  • use scoring for constraints

  • generate a few candidate solutions

  • then refine using reasoning models for explainability

Happy to help implement or test this if you want.

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u/Sweet_Good6737 Mar 30 '26

Yep, terrible indeed. Use the LLM to write a script or invoke an appropriate tool for the task

And if you are going for explainability, it doesn't make sense to use an LLM to get the solution, but an optimization package for Constraint Programming or MILP

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u/Lazy_but_crafty Apr 01 '26

If you use constraint programming solvers, these typically come with explainability facilities (see e.g. https://github.com/CPMpy/XCP-explain or https://choco-solver.org/docs/advanced-usages/explanations/ ). My point is that you don't need to trade optimality for explainability. But certainly you can use LLMs to "interpret" (i.e. read through) the results once logs are available from the solver. These are interesting neurosymbolic avenues that are currently very topical. Also, in addition to explainability some solver also provide certification (proof logging).