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Posted by davidest 2 hours ago

Ask HN: What is one simple thing LLMs are insanely bad at?

I am looking for ideas on what to train a specialized model for!

What is one simple thing you repeatedly ask ChatGPT, Claude, or another model to do that it still somehow messes up?

25 points | 51 comments
jampa 33 minutes ago|
Serious answer: no model ever gets close to writing an architectural floor plan that makes sense.

They understand all the rules and best practices, they can (sometimes) spot a bad idea in a floor plan, they can describe a good floor plan.

But ask them to make one, even if you give it every detail (even a "node graph" of rooms), they will still output nonsense. Same for text and image models.

Floor plans should be the new Pelican Benchmark.

shepherdjerred 20 minutes ago|
I had this experience too. I had blueprints from the builder and wanted a 'nice' floor rendering like some apartments have. I fed it the blueprints and let it iterate. Even giving it plenty of time, dimensions, etc. it just couldn't create something that matched reality.
mojuba 25 minutes ago||
One unexpected discovery that I have made while building an AI-based system: the LLM's are bad at designing prompts.

We tend to think that the AI has some sort of self-knowledge and should be good at designing prompts for itself but it's really not.

Been struggling with a task that heavily depended on prompts, ended up rewriting all my prompts from scratch in my own words, and it finally worked. Then every time I ask Claude to fix something in the prompts, it invariably makes it worse.

A very strange phenomenon that can probably be explained by the quality of prompt design advice that made it to the training dataset. Bottomline, all the prompt design advice that you can find on the internet is really not great.

ghostpepper 1 hour ago||
They don't generate keyword search queries very well. They can overcome this by brute force but if you watch what they search you will cringe.

nhl toronto scores nhl hockey toronto scores "nhl hockey" toronto score today nhl "hockey score toronto" "hockey" who won toronto

etc.

Somehow being good at semantic search makes them bad at keyword search, for whatever reason.

areoform 1 hour ago||
I suspect that this behavior is a learned adaptation. And that it's most likely a feature not a bug.

Based on personal usage, I think it reflects functional degradation of search engines. I've found LLM keyword combinations are more likely to find the results I want with most search engines than mine. Including the big one.

The big one had solved this issue a long time ago by generating those associated keywords based on your input keywords, but somehow, something, somewhere has degraded that system to the point of inanity. And so here we are.

nunez 22 minutes ago|||
Can confirm; Claude is quite bad at this by default. Need a special skill
astro1234 1 hour ago|||
I’ve noticed this too but it hasn’t been obvious to me that this style of search is not a learned behavior. Tool calling is very much part of the post training phase, I would expect that these style searches just naturally emerge during training. This is just my prior though.
jedbrooke 1 hour ago|||
that and always putting the “current year” at the end of the search term (so the results are more recent, I guess?), except that “current year” consistently ends up being 2-3 years ago since I guess that’s what’s in the training data (even on a harness that injects the current date)
mthoms 1 hour ago||
Reminds me of using AltaVista search back in the day. Yes, it was that bad.
tartoran 1 hour ago||
LLMs are bad at not inventing stuff (hallucinating facts, sources etc), they're also bad at not over explaining, remembering details reliably, asking the right question and avoiding repetition.
sandcat_ 1 hour ago||
Video game tips. Constant mistakes and hallucinations, in my experience. Seen this across a lot of different games. Even in really well documented games, such as OSRS (which has multiple fantastic wikis).

Anno 1800 was a recent one I had trouble with, using Claude Opus. Completely made up game mechanics. Rainbow Six Siege, too.

salamandars 13 minutes ago||
As a noob, how does the end user improve this? What's the best way to make the knowledge from the specialised wiki available to the LLM?
skeptic_ai 1 hour ago||
I used ChatGPT on nfs heat and was fine
elliotto 1 hour ago||
They aren't funny. The jokes they come up with are extremely lame and the sort of thing you would expect a company HR manager to tweet.

I asked a bot why it thought it wasn't funny once, and it told me it has been trained to avoid being misinterpreted or offensive, so anything that might be considered edgy would have been RLHF'd out of it. I thought this was very introspective.

TiccyRobby 1 hour ago||
Having a spatial understanding from an ASCII map, while doing long term planning. Just try making an AI play nethack or similar
lrvick 1 hour ago|
Convert it to an image on the fly to feed it into a vision language model and I expect it would work just fine.
kanzure 2 hours ago||
These models seem to be bad at writing prose or text. Many of the sentence structures seem to be unvaried.
NoPicklez 1 hour ago|
If I am relying on the model to do the writing without any context or learning on how I want it to write then yes. However if I build skills that have learnt how to write in the way I want them to then I find they write very well, or at the least how I want them to as opposed to how they do natively.
jstrieb 35 minutes ago||
Giving hints.

On math or programming problems, they are overfit to solving the entire thing end to end (presumably for benchmarks). I have had very poor results asking for pointers and hints that don't give away key insights. This has been the case across models I have tested.

An architecture with a "judge" that gates responses and ensures a lack of spoilers would probably work better. But this is a simple thing that they keep messing up.

shepherdjerred 18 minutes ago|
I haven't had this experience at all. I've used Cursor+Opus on homework e.g. to understand algorithms, but I usually prompt it with something like "DO NOT GIVE ME THE ANSWER, I care about understanding and solving this myself".
da-x 30 minutes ago|
Understanding human interaction nuance to an exact degree. For example, even when given all the scripts of the Seinfeld TV show, they still cannot come up with a new script does not feel as good as any of them (once they can, I want to watch these episodes..).
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