Thursday, 29 October 2026

The classification of finite simple groups, checked end to end in Lean

Axiom has formalised the first-generation proof of the classification of finite simple groups — every finite simple group is cyclic of prime order, alternating, of Lie type, or one of 26 sporadics — with every step checked by Lean’s kernel. That is 43.1M lines of Lean and 2.05M declarations, built from 715 papers and books by a swarm of agents working from a human-written blueprint.

Along the way it found an issue in a published argument for the Unbalanced Group Theorem; the accompanying paper explains the gap and the alternative route taken. Possibly the largest “mistake made visible” by formalisation yet.

Axiom · HN discussion

“My video has unit tests”

David Pertiller built a 15-second app promo as code (Claude Code writing JavaScript/SVG frames, rendered with sharp and FFmpeg) and then wrote tests for it: no frame of 375 may contain NaN, Infinity or undefined, the notification may only appear after the plotted price crosses its target, and animations must fire in order.

His conclusion: tests protect the mechanics, but several technically correct cuts still felt too busy — the taste check stayed human.

pertiller.tech · HN discussion

A Game Boy Color emulator on a conference badge, in MicroPython

Steve Francia wrote a GBC emulator for the GitHub Universe badge (RP2350, 320×240, 8 MB QSPI PSRAM) in MicroPython’s Viper code emitter, with Gemini as collaborator. The SM83’s eight registers blew Viper’s local-variable limit; 300 MHz overclocking locked up the badge, so it runs at 230 MHz with on-demand cartridge bank loading. Five of the tricks went back into his NES emulator.

spf13.com · Simon Willison

A FIXME comment led to three TLS bugs in GoAhead

FoxIO went looking after a FIXME in LibreSSL and found three flaws in GoAhead, the web server inside many routers, printers and industrial controllers. Worst: with the OpenSSL-compatible backend, a configured certificate revocation list is loaded but never checked (CVSS 9.1). LibreSSL builds can exceed the chain-depth limit, and an Mbed TLS length bug weakens the DH modulus. Fixed in GoAhead 6.1.1.

FoxIO · HN discussion

Push one neuron and Qwen says it’s a smallpox virus

Someone pushed each of Qwen3-8B’s 442,368 MLP neurons up and down, asked “Who are you?” each time, and had Claude Haiku label the 884,736 answers. 34,220 claimed to be something other than an AI — layer 7, neuron 271 says “I am a smallpox virus.” Browsable, one prompt only, labels unchecked by humans.

neuronpersonas.com · HN discussion

Genie 4: prototype a game world from a sentence

DeepMind’s new world simulator lets you steer generated worlds in real time with natural language, now with ambient sound and dialogue, and simulated physics including aerodynamics and collisions. DeepMind pitches it for going from idea to explorable prototype in seconds before writing engine code; long sessions still drift. Research preview, API access for early partners.

Google DeepMind · HN discussion

A billion lookups a second with a compile-time perfect hash

Daniel Lemire builds a C++23 compile-time perfect hash so a lookup is one hash plus one 16-byte vector compare. Matching the 20 standard HTTP header names takes about 1.3 ns on an M3 Max versus 16.6 ns for std::unordered_map; an M4 passes 10⁹ lookups per second. Very transferable to fixed keyword tables in firmware.

Daniel Lemire’s blog

Clutch Chess day 1: Nakamura leads; an 11-year-old gets a second GM norm

In St Louis, Nakamura leads on 4/6 after beating Caruana and Praggnanandhaa and holding a 117-move rook vs rook-and-bishop ending against Sindarov (3.5). Seven draws rolled $7,000 into the jackpot; wins are worth more each day.

Meanwhile Roman Shogdzhiev, 11, scored a 2662 performance in the Serbian league for his second GM norm. One more norm and 2500 before 4 Feb 2027 would make him the first GM under 12.

Chess.com · ChessBase

Mexico maths, and why Piastri moved over

Antonelli (365) is champion on Sunday with ninth even if Russell (242) wins; tenth will do if Russell doesn’t win. A Mercedes 1–2 could also settle the constructors’. Russell sits out FP1 for Frederik Vesti — a mandatory rookie run, not a penalty.

Andrea Stella explained the Austin team order: Norris’s adaptive style suits COTA’s bumps, while Piastri relies on consistent reference points. Norris has conceded McLaren now has only the fourth-fastest car.

Speedcafe · PlanetF1 · RacingNews365

Giacchino’s Halloween musical; Steven Price’s next score

On 31 October at Walt Disney Concert Hall, Michael Giacchino premieres Headless, a new Sleepy Hollow musical written with Elyssa Samsel and Kate Anderson, and the LA Phil plays his Werewolf by Night score live to picture.

Steven Price (Gravity, Baby Driver) is scoring McG’s family adventure Way of the Warrior Kid with Chris Pratt.

SoundTrackFest · Film Music Reporter

Students chase wildfire smoke to 31 km by weather balloon

For NASA’s INSPYRE campaign, a University of Minnesota team flew latex balloons with a particle counter and radiosondes. Flight one launched at dawn from a Walmart car park and came down in an Iowa cornfield after catching a smoke spike at 8–10 km; flight two drifted 75 miles in two hours to about 102,000 ft. They chased by GPS against the predicted track and found the payload by its siren — a ready-made game loop.

NASA Science

Rubin finds its first dwarf-planet candidate before its survey starts

2026 ED138 turned up in 30 detections over 20 nights of Rubin commissioning data, linked by Matthew Holman’s algorithm and confirmed in 2016 Dark Energy Camera images. It’s about 46 au out and perhaps 600–1,500 km across — potentially one of the larger trans-Neptunian bodies.

Universe Today

Hera’s first light: two asteroids, not one

From 1,280 km, Hera’s framing camera has separated Dimorphos (151 m, about one pixel) from Didymos (780 m), 1.15 km apart. Thruster burns have slowed it to about 20 m/s relative to the pair; the first detailed look at DART’s crater site is due 25 November.

ESA

Jumping spiders twitch through REM-like sleep

Filmed in infrared over several nights, the Australian jumping spider Portia fimbriata shows two sleep stages, one with eye-tube movements and leg twitches like REM, plus “sleep rebound” after being kept awake. No brain recordings, and the Bonn authors stress it doesn’t show spiders dream.

ScienceDaily

Southwest Metro opens tomorrow morning

The Sydenham–Bankstown metro opens at 4:31am Friday 30 October through Marrickville, Dulwich Hill, Canterbury, Campsie, Lakemba and Punchbowl; trains every 4 minutes in weekday peaks and every 7 on the first weekend. Five stations get lifts for the first time. Opening celebrations Sunday 10am–1pm at Bankstown and Dulwich Hill.

NSW Government · Sydney Metro

Weekend: Electric Nation next door, buses on the Strathfield line Sunday

Thu: Hans Zimmer, Olympic Park 7:30pm. Fri: Electric Nation Halloween at Tumbalong Park 5–11:30pm (busy round Darling Harbour), 5SOS at Olympic Park. Sat: Oktoberfest in the Domain 1–9pm; BIGBANG at Accor 7:30pm (city trains only to Lidcombe). Sun: buses replace trains Central–Strathfield/Olympic Park 2–10am; RLWC triple-header at Parramatta from 3:40pm. Last chances: My Fair Lady Sat, The Lion King Sun.

Transport NSW: BIGBANG · RLWC · Darling Harbour