Tonight's headline from the AI world comes from mathematics. The Clay Mathematics Institute has indicated that the Navier–Stokes problem, one of the seven Millennium Prize Problems, has "apparently been settled," and a formal review is now underway. Beyond that, the news spans a proposal for an open-source AI zone among BRICS nations, Superhuman's acquisition of Fathom, K2 Horizon's benchmark listing and criticism of its KV cache design, and research on editing actions in world models — a wide-ranging set of topics. Here is a roundup of today's news.
Navier–Stokes Problem "Apparently Settled" — Clay Institute Enters Formal Review
According to [The Decoder](https://the-decoder.com/clay-mathematics-institute-says-the-navier-stokes-millennium-prize-problem-has-apparently-been-settled/), the Clay Mathematics Institute has said that the Navier–Stokes problem has "apparently been settled" and is now conducting a formal review.
The Navier–Stokes problem is one of the Millennium Prize Problems, each carrying a $1 million prize, and it asks about the existence and smoothness of solutions to the equations that describe fluid motion. This is the biggest development since this blog reported on September 9 that "a claimed proof emerged as a candidate for a second Millennium Prize," and the key point this time is that the institute administering the prize itself referred to the problem as "apparently settled." The wording remains deliberately cautious, though, and there is no telling at this point how the review will rule. We will be watching to see whether this becomes the first feat of its kind since the Poincaré conjecture.
Xi Proposes Open-Source AI Zone for BRICS — Slowdown Calls Branded a "Cold War Tactic"
Chinese President Xi Jinping has proposed creating an open-source AI zone for BRICS nations, according to multiple international outlets including [CNBC](https://www.cnbc.com/2026/09/13/china-xi-ai-tech-brics.html) and [Reuters](https://www.reuters.com/business/aerospace-defense/xi-pushes-greater-brics-economic-ties-give-bloc-larger-global-role-2026-09-13/). Xi stressed the need for stronger cooperation, and the story is also generating discussion [on Reddit's r/LocalLLaMA](https://www.reddit.com/r/LocalLLaMA/comments/1wg4kpu/xi_promotes_open_source_ai_zone_among_brics/). If sharing and jointly developing open-source models actually moves forward within the BRICS framework, the impact on the local LLM community would be hard to ignore.
Around the same time, [Reuters reported](https://www.reuters.com/world/china/china-state-newspaper-blasts-anthropics-calls-slow-ai-cold-war-tactic-2026-09-14/) that a Chinese state-run newspaper blasted Anthropic's calls to slow AI development as a "Cold War tactic." The tone has sharpened further since the Chinese Foreign Ministry's "fearmongering" rebuttal we covered earlier, and the U.S.–China back-and-forth over slowdown arguments looks set to continue for the time being.
Superhuman Acquires Fathom — Productivity Tools Push Toward Agentic Work
According to [TechCrunch](https://techcrunch.com/2026/09/14/superhuman-acquires-yc-backed-notetaker-fathom-as-productivity-platforms-push-for-agentic-work/), email client Superhuman has acquired Fathom, a YC-backed AI notetaking tool. Fathom serves more than 400,000 monthly active users and has specialized in capturing notes from online meetings.
As background to the deal, TechCrunch points out that productivity platforms are competing to deliver "agentic work." Superhuman, which commands the two biggest media of daily work — email and meetings — appears to be aiming to broaden the scope in which its agents can operate by bringing meeting notes into the fold as context. We look forward to future announcements on how the combined product shapes up.
Full K2 Horizon Lineup Listed on AA — Harsh Words for the KV Cache Design
Our evening roundup covered "K2 Horizon 7B making waves on Reddit," and as a follow-up, the full lineup has now been listed on Artificial Analysis. According to [an analysis post on Reddit](https://www.reddit.com/r/LocalLLaMA/comments/1wg4a0u/k2_horizon_lineup_is_out_on_aa_and_once_again_aa/), on AA's intelligence-versus-parameter-count plot, the 0.9B and 375B underperform, the 3.7B and 7B are SOTA, and the 36B-A4B is regarded as SOTA on memory-bandwidth-limited hardware (Strix Halo, DGX Spark, and the like).
The poster, however, flags a problem: "the KV cache design is terrible." At 128k context with Q4_K_M quantization, the 36B-A4B reportedly consumes 6.7GiB for context, while the 7B and 3.7B each consume 5GiB. That is a huge gap compared with Qwen3.6-35B-A3B, which uses 0.7GiB for context under the same conditions, and MiniCPM5-2B at 1.5GiB. Even models that look good when compared by parameter count can rate very differently once RAM requirements enter the picture. The poster therefore argues that deployment-specific judgments are needed, along the lines of: "interesting for a host with exactly 16GB VRAM + 32GB RAM, but with 24GB VRAM, Qwen3.8-27B is faster, smarter, and also supports 256k context."
ActionSplice — Editing World-Model Actions Mid-Generation
On the research front, ActionSplice, a method for rewriting actions in a video world model mid-generation, was featured on [Hugging Face Daily Papers](https://huggingface.co/papers/2609.08230). In chunked-autoregressive world models, a change in the user's actions traditionally required rolling back and regenerating. In contrast, ActionSplice has a lightweight collector perform "counterfactual state transport (CST)" at the point of interruption, swapping in a new trajectory while keeping the world model and sampler frozen.
CST-R retargets the entire active chunk, while CST-T preserves the temporal prefix and edits only the suffix. In evaluations on minWM–Wan Action2V and HY-WM1.5, CST-R reduced rollback-relative LPIPS by 61.5% and 75.9% respectively, CST-T reduced suffix LPIPS by 56.1% and 77.5%, and the two achieved 2.73× and 1.69× speedups compared with waiting. This property — reflecting new inputs without restarting generation from scratch — seems directly tied to a future where world models are used interactively in games and simulations.
Wrapping Up
It was a night of wide-ranging news: a mathematical prize problem, geopolitics, an acquisition, local LLMs, and research. Both the outcome of the formal review of the "apparent settlement" and the concrete shape of the BRICS open-source AI zone are developments worth watching.