Understanding AI

The AtCoder World Tour Finals, held in Tokyo every year, is one of the most prestigious programming competitions in the world. It has two divisions. There’s a heuristic division where programmers compete to maximize performance on an open-ended task. And there’s an algorithmic division where contestants must find a way to efficiently compute exact solutions to mathematically challenging problems.

Over the last year, this newsletter has grown by nearly 200,000 readers — from 78,000 in June 2025 to 273,000 today. Our paid readership has also grown, but not nearly as fast. Today, fewer than 1% of you are paying subscribers. So in the coming months, I plan to begin showing ads to free readers (paid subscribers will continue to enjoy an ad-free experience). For ethical reasons, I won’t accept ads for companies we are likely to cover.

Ever since the Trump Administration forced Anthropic to pull its two most powerful models from the market on June 12, a big question has been whether Anthropic was being singled out for special treatment — or whether this would become a new policy for the AI industry as a whole.

Anthropic stunned the AI world on Friday by announcing it was revoking access to Claude Fable 5 and Mythos 5, the powerful new models it released just three days earlier. The government, Anthropic said, had “issued an export control directive to suspend all access to Fable 5 and Mythos 5 by any foreign national, whether inside or outside the United States.” Because Anthropic doesn’t have a way to limit access to Americans, this amounted to a de facto ban on the technology.

When Anthropic announced its latest model, Claude Fable 5, on Tuesday, a statement tucked away on page 13 of the attracted an immediate outcry. AI researcher Nathan Lambert called it “appalling.” Dean Ball, who worked on AI policy in the Trump White House, wrote that it was “shockingly hostile.” Many others joinedinthepile-on. The announcement that got everyone so mad?

We’re hosting a happy hour for DC-area readers of Understanding AI (and listeners to my podcast, AI Summer) on June 23 at The Crown & Crow. We’ll start at 5:30pm, and I expect to stay until 8:00pm. We’d love to see you.

On Tuesday, Anthropic released two new models — Claude Mythos 5 and Claude Fable 5. Under the hood, the two models are very similar. Both are variants of Claude Mythos Preview, the model Anthropic announced — but didn’t release publicly — two months ago. What differentiates them is how they’re being released. The new version of Mythos, like the original, will only be available to handpicked organizations under Project Glasswing. These trusted partners will have relatively unfettered access.

Hello paying subscribers! Today is a big day here at Understanding AI headquarters: it’s Kai’s first day as an Understanding AI employee. Until Friday, his work was supported by the Tarbell Center for AI Journalism. Now I’m paying his salary, which means that your subscription dollars are making his work possible.

Last week, OpenAI announced that an internal AI model had disproved the Erdős unit distance conjecture, a famous problem in discrete geometry that had stumped human mathematicians for the last 80 years. OpenAI gave several mathematicians early access to the result and published their reactions.

Last month I got to check out a self-driving car unlike any I’d seen before. The roof had a Waymo-like rack of sensors. Inside, the doors had small video screens instead of side mirrors. At the touch of a button, the rectangular steering wheel folded into the dashboard and a video screen slid in front of it, putting the car into self-driving mode. The prototype vehicle, made by a startup called Tensor, was parked on a San Francisco street outside the Ride AI conference.