Last Week in AI

#235 - Sonnet 4.6, Deep-thinking tokens, Anthropic vs Pentagon

Mar 3, 2026
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Summary

The episode reviews major AI model releases and benchmark leaps (Anthropic’s Sonnet 4.6 with a 1M-token context window and Google’s Gemini 3.1 Pro showing a large ARC-AGI-2 improvement) alongside product features like Anthropic’s Claude Code and multi-agent demos from Perplexity and xAI. It covers significant compute and business developments, including Meta’s reported large AMD chip procurement deal and large funding rounds for specialized AI chip and world-model startups. The hosts discuss training and research advances — a masking/skip-update optimizer (Magma) that reduces final loss, mechanistic interpretability results (low-dimensional scalar manifolds for counts), and the notion of deep-thinking tokens that correlate with accuracy. They also examine system-level and policy issues: model attractor states and failure modes in multi-agent/long-running interactions, infrastructure disputes around Stargate data centers, and geopolitical questions about chip supply, export controls, and DoD use of commercial models.

Key Takeaways

  • 1Anthropic’s Sonnet 4.6 and similar cadence improvements materially expand production capabilities by supporting 1 million-token contexts.
  • 2Multimodality is a competitive differentiator — Gemini 3.1 Pro’s large ARC-AGI-2 jump highlights that visual reasoning substantially improves performance on certain benchmarks.
  • 3Simple training tricks like masking/skip-update optimizers (e.g., Magma) can yield large, consistent reductions in final loss across model sizes.
  • 4Deep-thinking tokens — tokens whose predictive distribution continues to shift in later layers — correlate with higher answer accuracy and can be used to manage reasoning depth/cost tradeoffs.
  • 5Models have attractor states and low-dimensional internal representations, creating both interpretability opportunities and multi-agent failure modes.

Notable Quotes

"Another increase in the context size up to one million, which is a very big deal if you're using these in production."

"Gemini 3.1 Pro gets at 77.1 on ARC‑AGI2 compared to Gemini 3 Pro's 31.1%."

"There's a deal where they're going to spend up to a hundred billion dollars on chips over multiple years using AMD's MI540 GPUs ... it's giving Meta like a 10% stake in AMD ... contingent on performance ... requires AMD stock to hit $600 a share which is more than triple its current price."

"This reduces final loss in this case by 19% and 9% over two options Adam and one ... for every model from 60 million to one billion the final loss performance is just lower across the board."

"If it's the case that these models have attractor states then we ought to expect agents that are running off these models like to kind of run into these attractor states if they have to interact over long periods of time."

"Character counts live on basically a curve one dimensional manifold."

"They show that it's possible to, using the performance of a model alone on a given task and some model of how that correlates to human performance, you can predict how long a human would take given a model performance alone."

"There’s over 16 million exchanges with Claude through approximately 24,000 fraudulent accounts."