[HN Gopher] AbsenceBench: Language models can't tell what's missing
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       AbsenceBench: Language models can't tell what's missing
        
       Author : JnBrymn
       Score  : 27 points
       Date   : 2025-06-20 22:26 UTC (33 minutes ago)
        
 (HTM) web link (arxiv.org)
 (TXT) w3m dump (arxiv.org)
        
       | AlienRobot wrote:
       | Unrelated to the paper, which is about asking LLM's to figure out
       | which parts of a document were removed, but my assumption has
       | been that to an LLM there is nothing "missing" in the sense that
       | any input leads to valid computation and output.
       | 
       | For example, I asked ChatGPT to explain something I typed
       | randomly
       | 
       | >It looks like you've entered "dosfi8q3anfdfiqr", which appears
       | to be a random string or perhaps a typo--it's not a recognized
       | acronym, code, or term in any common context I'm aware of. Could
       | you share a bit more about where you found this?
       | 
       | Although the answer is correct, my point is that anything you
       | give to the LLM is going to be put under some bucket. The LLM
       | can't say "I don't know what that is." Instead it says "that is a
       | random string." As far as the LLM is concerned, it knows every
       | possible input and concept that anyone could ever type into it,
       | it's just that its "understanding" of what that means (after the
       | tokens have gone through the neural network) doesn't necessarily
       | match what any human being thinks it means.
        
       | cs702 wrote:
       | Interesting. Even the most recent models perform relatively
       | poorly when asked to identify which information in a context has
       | been removed, given access to both the original and edited
       | contexts.
       | 
       | The authors posit that poor performance is due to the fact that
       | the attention mechanism of Transformers cannot attend to the
       | removed tokens, because there are no keys for them!
       | 
       | Thank you for sharing on HN.
        
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       (page generated 2025-06-20 23:00 UTC)