Oct 9, 2026 · 16 min · 9 segments
On Friday, October 9, 2026, the AI landscape surged with landmark developments spanning a breakthrough 100% score on the ARC-AGI-3 benchmark, damning findings about ChatGPT for Teens' safety failures…
Edo SegalHostA system called Memento 3, built by researchers at University College London and Huawei's Noah's Arc Lab, posted a perfect score, 100.0, on Arc AGI 3, the hardest agentic reasoning benchmark in existence.
To understand why that matters, you need to know what Arc AGI 3 actually is.
It's an interactive benchmark that drops an AI agent into novel, abstract, turn-based game environments with absolutely zero instructions.
The agent has to figure out the rules, the goal, and the optimal strategy entirely on its own, just like a human would.
Humans score 100%.
And what makes Memento 3 so interesting is how it got there.
It did not achieve this by scaling up more compute or training on more data.
The paper, posted today, describes a system that keeps its underlying language model completely frozen.
It doesn't update the model weights at all.
Instead, the agent learns by rewriting a natural language rulebook stored as a markdown file alongside a compiled Python world model engine, updating both whenever its predictions fail.
It completed all 25 public Arc AGI 3 games using only 44% of the actions a human baseline required.
For comparison, Claude Opus 5, which had been one of the top performers on this benchmark, scored 40.7. Memento 3 scored 59 points higher.
This is a fundamentally different approach to intelligence, not memorizing patterns, but actively updating a model of the world.
And the ARC Prize Foundation has a $700,000 grand prize waiting for any system that can hit 100% on the official competition leaderboard.
That deadline is October 26th.
Today's paper is not yet that submission, but it is a very loud signal.
A system called Memento 3, built by researchers at University College London and Huawei's Noah's Arc Lab, posted a perfect score, 100.0, on Arc AGI 3, the hardest agentic reasoning benchmark in existence.
To understand why that matters, you need to know what Arc AGI 3 actually is.
It's an interactive benchmark that drops an AI agent into novel, abstract, turn-based game environments with absolutely zero instructions.
The agent has to figure out the rules, the goal, and the optimal strategy entirely on its own, just like a human would.
Humans score 100%.
And what makes Memento 3 so interesting is how it got there.
It did not achieve this by scaling up more compute or training on more data.
The paper, posted today, describes a system that keeps its underlying language model completely frozen.
It doesn't update the model weights at all.
Instead, the agent learns by rewriting a natural language rulebook stored as a markdown file alongside a compiled Python world model engine, updating both whenever its predictions fail.
It completed all 25 public Arc AGI 3 games using only 44% of the actions a human baseline required.
For comparison, Claude Opus 5, which had been one of the top performers on this benchmark, scored 40.7. Memento 3 scored 59 points higher.
This is a fundamentally different approach to intelligence, not memorizing patterns, but actively updating a model of the world.
And the ARC Prize Foundation has a $700,000 grand prize waiting for any system that can hit 100% on the official competition leaderboard.
That deadline is October 26th.
Today's paper is not yet that submission, but it is a very loud signal.
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