LLM Classification Is Feature Engineering

(minimallysufficient.com)

32 points | by minsufficient 1 hour ago

7 comments

  • softwaredoug 40 minutes ago
    In my work on LLM as a judge, I prefer to use LLM decisions as features in a downstream classic ML model for the final decision. It works really well

    https://softwaredoug.com/blog/2025/01/21/llm-judge-decision-...

  • twelfthnight 35 minutes ago
    Why not use a text embedder for the unstructured data and concatenate with the structured data?

    For example you could freeze most of the layers of the embedder but let the final ones learn. Then you wouldn’t need to do either feature or prompt engineering?

  • xerlait 36 minutes ago
    Why does he first ask to label "ironic" or "not", and then answer the feature questions? Wouldn't it be better to reverse the order?
  • elendilm 10 minutes ago
    Well timed article. :)
  • drabbiticus 27 minutes ago
    I really wish people would define terms when using math. What is y? What is LLM(x)? Presumably it evaluates to some real number so that it can be fed to the logistic sigmoid function. If it is the logistic function, then why does beta going to infinity matter? It seems to just collapse the output of the sigmoid function to 1 and make the value of LLM(x) meaningless instead of their claim that it recovers the LLM classifier. What is the function I()?

    Maybe these are well understood terms in some field? Maybe I'm just lost?

  • dist-epoch 28 minutes ago
    > Calibration / Threshold Control

    The amount of thinking is relatively calibrated. Ask an obvious classification, you get an instant answer. Ask a tricky one, much more thinking.

  • ltbarcly3 53 minutes ago
    I don't understand the point they are trying to make.

    It's very often (always?) the case that something general also solves particular problems.

        A sorting algorithm is an implementation of min()
    
        A parser also is a syntax checker.
    
        A route planner is a reachability checker. 
    
        A computer algebra system is a basic arithmetic calculator.
    
        A general constraint solver is a Soduku hint maker.
    
    
    It's true that LLM output can be used as an input to another classifier, this is also true of any classifier. The improvement on top of the straight LLM classification is relatively small, and I would argue that working on the prompt or just including in the prompt for the LLM what features might be useful to consider would likely work even better.

    Fundamentally I read this article as: We want to build a simpler, dumbed down clone of Mathematica, so we cobbled together the following pieces... We also needed a way to do arithmetic, so we also include a copy of Mathematica to do basic arithmetic.

    • michi883 50 minutes ago
      I took the point as: don't make the LLM the classifier. Use it to turn messy input into useful features, then let a normal model make the actual decision. That gives you thresholds/calibration you can inspect.

      What I'm not sure about is how stable those features are when you switch the underlying LLM or model version.