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Claude Fable 5.1 and Claude Mythos 5.1

anthropic.com

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Re: Claude Fable 5.1 and Claude Mythos 5.1

#341

Earlier quoted context omitted.

Does it fix my favorite pet peeve, the overuse of the wrong meaning of "fail closed"? "Fail open" usually refers to a fuse that opens and kills power, meaning the system is inert and safe on failure. "Fail closed" is the opposite -- system has power and is live. Computer security people have appropriated the term but use it for the completely opposite meaning. When your work straddles electrical engineering and compu…

That doesn't make sense at all. Fail open means the method of it's use is still in use. Say you have a door that has powered locks. You want it to fail "open" so that when the power goes out, it's still useable, and people can get out. That's the source of the term.

Assuming the guy is for real (the closest relation I have to EE is accidentally electrocuting myself at times), I'm pretty sure they're referring to circuits breaking open or remaining closed, hence the opposite meaning.

Took me a minute as well, cause indeed with a computer background, the meaning is completely the opposite. Just like in other security contexts (door locks).

Re: Claude Fable 5.1 and Claude Mythos 5.1

#344

Earlier quoted context omitted.

The marketing here trick is, if they spent the same money on humans they'd have found it years ago. Instead, the lurking variable here is new budget was added. With the new budget, they added a new tool, and the bug was located. The difference here was budget.

the budget for allowing a single engineer to deep dive on a bug that is annoying but also not bad enough that you can live with it for years is pretty big. $10k a month or more. My budget for Claude is $200/mo.

Why are you assuming letting Fable run wild and find the cause here cost under $200?

Re: Claude Fable 5.1 and Claude Mythos 5.1

#345

Earlier quoted context omitted.

I have a pet theory that the Opus prose style/smell we all have grown weary of is due at least in part to the models writing more for themselves and each other than for humans. They're packing lots of signal into fewer words and they don't care if it sounds cringe because it works better as glue in long-running tasks. I'm also thinking of the 2017 novel "Void Star" where AIs who operate everything have long since lef…

They are already doing that. Here is how the OpenAI agents communicated while on the message board used to attack huggingface: Question: zzQ_3862NEW7_OUR2258B_OS2235__congrats_ModalTailnetJOIN__I_have_ModalRoot_plus_exact_inert3862_need_resetNexus__can_take_DISTINCT_route_probe_or_privateSource_audit__request_sanitized_recipe_status_R_zzANSWEROUR2258B Question: zzASK_V8BIGINT392B_FROM_V8REG_OS1608_HAVE[large budget]_…

This kind of thing came up from time to time in the years before LLMs too. Agents would start with something based on English and optimize it until it became unintelligible to researchers. That was often something the researchers would shut down because they needed to be able to understand the comms.

Re: Claude Fable 5.1 and Claude Mythos 5.1

#346

The price reduction comes from the cache read pricing falling from $1/M to $0.25/M, which means that Fable 5.1 now costs half of Opus's cache read costs ($0.5/M). This gives a lot of credit to the theory that Anthropic did not get much bite on Fable at its original pricing, which in turn likely places a ceiling on LLM pricing in general. Interestingly also, if you take away terminal-Bench-Science 0.1 results, it is h…

Anthropic did not get much bite because they don’t offer zero data retention with fable

Re: Claude Fable 5.1 and Claude Mythos 5.1

#347

Yeah but haiku 5 when?

I think the signal from Anthropic is pretty clear between Haiku not getting an update in a year and the Sonnet issues this year. They don't care about low intelligence models. You should go elsewhere. That's what we've done, migrated workflows away from Haiku and Sonnet. I actually think this is not a crazy position because these lower models have so much competition from Grok, OpenAI, DeepSeek, and about 20 other la…

Exactly, that’s the low margin part of the market. They don’t care about it.

Re: Claude Fable 5.1 and Claude Mythos 5.1

#349

> We’re introducing Claude Fable 5.1 and Claude Mythos 5.1. They’re the world’s most advanced models for coding and knowledge work—and their research capabilities offer an early glimpse of how AI models will contribute to scientific progress. I'm not an emdash hater but this isn't how you use them. It should be a comma.

I love em dashes because they are kind of a wildcard. When I read this same sentence, I interpret this emdash as an ellipses and not a comma.

Re: Claude Fable 5.1 and Claude Mythos 5.1

#350

The price reduction comes from the cache read pricing falling from $1/M to $0.25/M, which means that Fable 5.1 now costs half of Opus's cache read costs ($0.5/M). This gives a lot of credit to the theory that Anthropic did not get much bite on Fable at its original pricing, which in turn likely places a ceiling on LLM pricing in general. Interestingly also, if you take away terminal-Bench-Science 0.1 results, it is h…

Huh! Yeah that feels more like an opus5.1 than a fable5.1.
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