Research @GoogleDeepMind. Prev @ContextualAI, @MIT_CBMM, @evl_uic, @UNIoficial 🇵🇪

San Francisco, CA
Joined January 2020
Late life update: Got my O1 visa 🇺🇸 and joined @GoogleDeepMind Happy to have contributed to the release of the recent Gemini model and especially excited about knowledge work progress (beyond coding)!
Introducing Gemini 4 Argon – our new frontier model. It’s built for complex workflows across coding, enterprise knowledge work, and cybersecurity defense – rolling out today to a set of trusted testers through our Fairwind Program.
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William Berrios retweeted
I defended my Ph.D. @stanfordnlp a few months ago, and recently started @AnthropicAI on the Interpretability team! (pictured: my awesome defence committee members)
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William Berrios retweeted
AI models can be as convincing as a lawyer, but can they complete the complex multi-step reasoning a real legal matter requires? Today we're excited to introduce LegalReasonBench, a new benchmark to explore this question and test models on realistic, long-horizon legal matters authored by practicing attorneys. More info in thread đź§µ
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William Berrios retweeted
Everyone wants to have solved a hard problem, but almost nobody wants to live inside the grind of actually solving it. The breakthroughs belong to the few who are obsessed with the process, not just the idea of the outcome
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William Berrios retweeted
We're hiring across many roles at Trillium Labs, @trillium_labs, to build the open scientific ecosystem for LLMs. Most important hires right now (ideally with start dates soon): * Full time post-training researchers * Engineers with experience with popular open-source libraries (megatron, MILES, sglang, Tinker, etc.) * Mission-aligned generalists, non-profit ops, etc. * Student researchers I'm also personally interviewing for MATS right now, which will be very aligned research. Please reply, email me, DM me, etc AND submit the form on our website. Excited to build this team. All early hires will work directly with me on all sorts of fun puzzles to rapidly scale our impact.
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William Berrios retweeted
the fact that frontier models are bad at chess (< 2200 elo) is a fascinating case study in jagged intelligence (which maybe provides ample copium about the post-agi economy) reasoning from first principles/public evidence: (1) it should be easy to post-train for chess elo -- super verifiable, tons of data (human games, self-play), free turn-level reward (stockfish), relatively cheap outcome-level signal (30-40 moves), easier credit-assignment than other tasks. (2) therefore, labs don't care about chess elo / aren't trying to post-train for it. and this has two implications: (a) post-training for core objectives (coding, math, science, knowledge work, rsi, etc.) still plateaus at ~95th percentile human ability on an ood task, even on a relatively simple/verifiable env like chess (b) there is no value/negative value for post-training for chess. either (i) it hurts core objectives/metrics (maybe leading too overthinking?), (ii) it takes compute/time away from core objectives. the core implication of (b) is that labs are/will prioritize pushing a narrow set of core objectives rather than smoothening the jagged frontier (even when its easy to do so, eg chess) (3) if it generalizes that (a) general models plateau relative to specialized models, (b) labs will prioritize performance on narrow set of core objectives it follows that (a) there will be no one-size-fits-all model/agent. there will continue to be value in specialization (b) the (foundational) model layer will not dominate everything. there will remain headroom in many non-core capabilities, and opportunities for specialized post-training, data/learning signal, harness/context/system-level optimization, etc.
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William Berrios retweeted
🚨Intern Hiring for Summer 2027🚨 I am looking for a Research Intern to join us at @GoogleDeepMind in Mountain View, California! The project will be exploring both theoretical and empirical aspects of continual learning in deep network. Apply here: forms.gle/HmXExwWBguRiT1edA
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William Berrios retweeted
sorry for the delay, we’ll work faster here on :)
Introducing Gemini 4 Argon – our new frontier model. It’s built for complex workflows across coding, enterprise knowledge work, and cybersecurity defense – rolling out today to a set of trusted testers through our Fairwind Program.
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William Berrios retweeted
Really excited about this one! Knowledge work (beyond coding) is really the crucial frontier for AGI.
Lots of discussion out there about our next model(!), so I wanted to give an early look as soon as possible. Introducing Gemini 4 Argon! It shows frontier performance in complex workflows, cyber defense and software engineering. Teams are using it extensively at Google, from coding to quantum computing, great feedback. Here’s a look at the benchmarks:
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William Berrios retweeted
Lots of discussion out there about our next model(!), so I wanted to give an early look as soon as possible. Introducing Gemini 4 Argon! It shows frontier performance in complex workflows, cyber defense and software engineering. Teams are using it extensively at Google, from coding to quantum computing, great feedback. Here’s a look at the benchmarks:
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William Berrios retweeted
Gemini 4 Argon, our new frontier model. Up to 1M output tokens, up from 64K. $2 in / $10 out at launch. In testing with trusted partners. Developer access as soon as possible. 👇🏻 blog.google/innovation-and-a…
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William Berrios retweeted
proud to have played a role in making this model good
Introducing Gemini 4 Argon – our new frontier model. It’s built for complex workflows across coding, enterprise knowledge work, and cybersecurity defense – rolling out today to a set of trusted testers through our Fairwind Program.
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William Berrios retweeted
Having a disgusting laptop is a sign of a cracked engineer
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William Berrios retweeted
rented an entire cinema to build with Claude
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🧵New paper: Matryoshka LM Suites Instead of training all models of a suite independently, we nest them within a single architecture and train the suite in a single run => much less compute, same performance Also allows free distillation, better speculative decoding & more 👇
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William Berrios retweeted
no I'm not mad at you im just Giving You The Feedback Directly This is a sign of great respect in my culture
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William Berrios retweeted
We can finally talk about it: We found a way to extract hidden reasoning of frontier models using a vulnerability in the APIs of every frontier AI company. We verified that our reasoning token count matches billed API thinking tokens 1:1 for most of the prompts we queried.
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William Berrios retweeted
Every successful scientific project eventually enters a battle-testing phase in which the team is actively trying to show that their results don't hold. In a new post, @mmooritz and I describe how to ensure that this key process flourishes in an era of agentic science.
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William Berrios retweeted
I’m hiring! Come join our team at Google DeepMind in London or Mountain View to work on Gemini agent post-training. We are looking for Research Scientists and Research Engineers interested in advancing the capabilities of AI agents. Please apply here: google.com/about/careers/app…
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