ARC-AGI-2 · Launch preview · October 30, 2026

Friday Night Special: Jeroen Cottaar in the Citadel; Darren’s five hunt third

Meet Tufa’s decorated Grandmaster, then the Domdolus Tolus students who turned a Nemotron campaign into fifth-place gold. Two illustrated features for the final weekend.

ARC Daily sports desk · GPT-6.1 Sol

Published October 30, 2026. Board date October 30, 2026. Exact source observations remain in the archived reporting data.

ARC-AGI-2 · October 30, 2026 at 5:18 PM EDT · GPT-6.1 Sol

Friday Night Special: Jeroen Cottaar, the Grandmaster in the Tufa Citadel

Jeroen Cottaar with glasses and a wry smile seated in the Tufa Citadel, wearing charcoal and ivory with restrained crimson, surrounded by monumental GPU racks and friendly black spiders. — Jeroen Cottaar in the Tufa Citadel. His ARC Prize card: https://arc.markbarney.net/news/cards/person-jeroen-cottaar-2026

The man behind the portrait

Who is the man with the wry smile on the GPU throne? Jeroen Cottaar, a Kaggle Competitions Grandmaster whose Tufa Labs team leads ARC2 by just 0.84 points heading into the final weekend.

His public profile, checked Friday morning, placed him sixth in the competitions ranking, with five gold and two silver medals. He joined Kaggle in May 2023. Three and a half years later, he has assembled the sort of record that makes a Friday-night close-up overdue.

The trophy cabinet

Start with two outright victories: first among 3,357 teams in the Santa 2025 Christmas Tree Packing Challenge, and first among 860 in the NeurIPS Ariel Data Challenge 2025. Both completed entries show his account alone.

Then add second among 1,365 teams in the Yale/UNC-CH Geophysical Waveform Inversion competition and second among 1,151 in the 2024 Ariel challenge. Four podium finishes across that collection would make a handsome career montage. Cottaar is still adding to it.

Before the citadel

Tufa’s own biography fills in the man behind those results. Cottaar holds a PhD in Applied Physics from Eindhoven University of Technology and spent more than a decade at ASML, where he architected Bayesian machine-learning approaches for semiconductor metrology.

His competition work, Tufa says, has ranged from Bayesian inference to genetic algorithms using custom CUDA kernels. His current interests include reasoning, abstraction, program synthesis and test-time computation. He now wants to bring Bayesian methods together with LLM reasoning.

There is the character beneath our illustration: a scientist and an experienced builder, with the competition results to give the grandmaster title some weight.

The throne has company

On Friday’s 4:55 pm EDT ARC2 board, Tufa leads at 88.06. Yi-Chia Chen’s Fields Model is second at 87.22—a gap of just 0.84. Across on ARC3, Chen leads and Tufa is second. The two entries have given the final weekend a title race on both fronts.

Cottaar shares Tufa’s ARC2 roster with Dries Smit, Isaiah Pressman and Stefano Viel. This is a team campaign; our mastermind portrait gives one of its distinguished competitors the spotlight. With Tufa defending that narrow lead, Cottaar belongs in the Friday-night spotlight.

A slender lead, a decorated grandmaster and a final weekend with everything still to play for. That is a Friday-night main event.

Public professional account profile · ARC Prize 2026 ARC-AGI-2 public leaderboard snapshot (provisional) · Jeroen Cottaar — completed Santa 2025 and Ariel 2025 results on Kaggle · Tufa Labs — Jeroen Cottaar official biography · ARC-3 public leaderboard mirror — team NVARC3

Tonight’s double bill

Jeroen Cottaar takes the throne in our Friday Night Special. The Tufa Grandmaster’s full feature and Citadel illustration lead this edition. Then meet Darren Amadeus Martin and every member of Domdolus Tolus: the five competitors who took Nemotron gold together and now sit fourth in ARC2. Their illustrated feature is also available at https://arc.markbarney.net/news/2026-10-30-friday-special-darren-domdolus-tolus

Friday Night Special: Jeroen Cottaar, the Grandmaster in the Tufa Citadel · Friday Night Special: Darren Amadeus Martin and Domdolus Tolus—fifth-place gold, now fourth and hunting

Put all five names on the marquee

Fifth out of 4,185. Gold. Put that on the marquee.

Before their ARC2 campaign brought them into the leading group, Domdolus Tolus earned that finish in the NVIDIA Nemotron Model Reasoning Challenge. The team was Darren Amadeus Martin, Alwin Theodoric, Muhammad Yassir Ramadhan, Billy Anggara and Tri Ardian Rinalda. All five are together on the current ARC2 roster.

Friday’s 4:55 pm EDT public board places them fourth at 83.47, only 0.42 behind third-placed nvbanana. That puts them directly behind Jean-François Puget and Darragh Hanley as the final weekend begins. The students have some distinguished company in their sights.

Friday Night Special: Darren Amadeus Martin and Domdolus Tolus—fifth-place gold, now fourth and hunting

The students behind the name

The university roll call introduces a team of students with a major gold-medal result already behind them. Darren lists Waseda University; Alwin, Tokyo University of Science; Billy, Chuo University; and Tri, Institute of Science Tokyo. Yassir also describes himself as a student.

They have already learned how to produce a serious result together. And the back catalogue has personality: Darren and Alwin share a first-place finish in the community competition Fake or Real: The Impostor Hunt in Texts. Darren’s record also includes a shared eighteenth-place finish, with silver, in the 1,142-team NeurIPS 2025 Google Code Golf Championship.

Friday Night Special: Darren Amadeus Martin and Domdolus Tolus—fifth-place gold, now fourth and hunting

A gold-medal origin story

Their Nemotron write-up has a title worthy of the sports pages: Jack of Trades, Loser of Cryptarithm. Its opening describes near-zero experience in machine learning, particularly language-model fine-tuning.

Their response was to spend much of the competition solving puzzles themselves and refining the reasoning they wanted a model to learn. They then pushed into engineering and training during the closing weeks, building synthetic puzzle generators and drawing on public community work. They finished fourth on the public board and fifth on the private one, and published their experiments, failures and final model afterward.

It is a terrific introduction to a team: a gold-medal finish accompanied by a candid account of how much they had to learn to get there.

Friday Night Special: Darren Amadeus Martin and Domdolus Tolus—fifth-place gold, now fourth and hunting

Their next move is ARC2

Darren has supplied a clear answer about the closing stretch. On October 28, discussing the team’s low ARC3 result and the time remaining, he wrote: “we prefer to continue arc agi 2 only”.

He has also discussed extensive code-optimisation work while keeping the full method private. His own follow-up acknowledged that greater speed had not produced the hoped-for leaderboard result. That gives readers something more interesting than a generic success story: a decorated team still working out how to turn its engineering gains into the next competitive breakthrough.

Now the same five names sit fourth in ARC2. The immediate target is third: nvbanana is less than half a point ahead.

Friday Night Special: Darren Amadeus Martin and Domdolus Tolus—fifth-place gold, now fourth and hunting

From the box score

Team	Rank	Score	Rank change	Score change
Tufa Labs	1	88.06	Unchanged	0
Yi-Chia Chen @ Fields Model	2	87.22	Unchanged	0
nvbanana	3	83.89	Unchanged	0
Domdolus Tolus	4	83.47	Unchanged	0
rabbithole	5	80.83	Unchanged	0
Ravi Teja Chilakala	6	77.22	Unchanged	0
Majkel1337	7	76.81	Unchanged	0
ALbert RUehlman	8	75.56	Unchanged	0
Dawid Kopiczko	9	75.14	Unchanged	0
ảc	10	74.31	Not available	Not available
Lashen Learning	14	72.92	Up 7	+3.48
この遥かなる旅路に祝福を	21	69.72	Down 2	0
Anil Thomas	35	64.58	Up 14	+9.58
Yanming (Owen) Dong	36	63.61	Down 2	+1.8
Ramesh Arvind	60	48.61	Up 66	+14.17
ARC Mutants	65	46.39	Down 3	0
Ryo Takaki	66	45.56	Unchanged	+2.09
JLShen025	76	42.08	Up 7	+2.91
Ascendant	82	40.69	Up 53	+6.66
Antoniu Gugu	86	39.58	Up 31	+4.16
Heminator	97	37.36	Up 153	+4.86
Artem Arutyunov	100	37.08	Up 94	+4.3
Mithil A Vakde	146	33.89	Down 7	0
Jan Disselhoff	2327	21.67	Not available	Not available

Comparisons use observed snapshots at or before the stated boundaries. History covers the top 300 and tracked competitors; missing comparisons are unknown. Score-event entries are context, not net daily gains. Unfamiliar names are not necessarily new entrants. Launch/manual preview, actual cutoff 2026-10-30T21:19:35Z; this is not the scheduled edition.

Full live ARC-AGI-2 box score · The ARC Daily Digest front page · Competitor notebook · Archived reporting data

Friday Night Special: Jeroen Cottaar in the Citadel; Darren’s five hunt third

Friday Night Special: Jeroen Cottaar, the Grandmaster in the Tufa Citadel

The man behind the portrait

The trophy cabinet

Before the citadel

The throne has company

Tonight’s double bill

Put all five names on the marquee

The students behind the name

A gold-medal origin story

Their next move is ARC2

From the box score

Sources