Thurston's 24 questions

Per-problem resolution timeline

Open problems sit on the right edge. Hover a point for resolver and notes.

Definition

William Thurston closed his 1982 survey of three-dimensional manifolds, Kleinian groups and hyperbolic geometry with twenty-four questions. This ledger scores each question as one row, with the status and year read from the Wikipedia table named in the source column, cross-checked against Agol's public status note. There is no subproblem splitting and no contested classification: twenty-two rows are resolved and two are open (question 19, on arithmetic quotients of hyperbolic space, and question 23, on the rational independence of hyperbolic volumes).

A "discovery" in this series is a row moving to resolved, dated by the year the source account gives. Two dating conventions apply and are stated in the rows' notes: where the source gives a span rather than a year, the resolved_year is the end of the span (rows 4, 5 and 14), and the three software questions (20–22) are dated at a conventional 2000 for work the source places in the 1990s and 2000s.

Facts

The collection-wide cumulative index redraws the ledger as rows remaining:

Rows remaining without a dated resolution.

1 — Geometrization conjecture

"Solved by Grigori Perelman using Ricci flow with surgery." — Wikipedia, Thurston's 24 questions, question 1, read 2026-08-14

2 — Finite group actions isometric

"Solved by Meeks, Scott, Dinkelbach, and Leeb." — Wikipedia, Thurston's 24 questions, question 2, read 2026-08-14

3 — Orbifold geometrization

"Solved by Boileau, Leeb, and Porti." — Wikipedia, Thurston's 24 questions, question 3, read 2026-08-14

4 — Hyperbolic Dehn surgery global theory

"Resolved through work of Agol, Lackenby, and others." — Wikipedia, Thurston's 24 questions, question 4, read 2026-08-14

5 — Kleinian groups geometrically tame

"Solved through work of Bonahon and Canary." — Wikipedia, Thurston's 24 questions, question 5, read 2026-08-14

6 — Kleinian groups as limits of geometrically finite

"Solved by Namazi-Souto and Ohshika" — Wikipedia, Thurston's 24 questions, question 6, read 2026-08-14

7 — Schottky groups and their limits

"Resolved through work of Brock, Canary, and Minsky." — Wikipedia, Thurston's 24 questions, question 7, read 2026-08-14

8 — Limits of quasi-Fuchsian groups with accidental parabolics

"Solved by Anderson and Canary." — Wikipedia, Thurston's 24 questions, question 8, read 2026-08-14

9 — Kleinian groups topologically tame

"Solved independently by Agol and by Calegari-Gabai." — Wikipedia, Thurston's 24 questions, question 9, read 2026-08-14

10 — Ahlfors measure-zero problem

"Solved as consequence of geometric tameness." — Wikipedia, Thurston's 24 questions, question 10, read 2026-08-14

11 — Ending lamination conjecture

"Solved by Brock, Canary, and Minsky." — Wikipedia, Thurston's 24 questions, question 11, read 2026-08-14

12 — Quasi-isometry type of Kleinian groups

"Solved with ending lamination theorem." — Wikipedia, Thurston's 24 questions, question 12, read 2026-08-14

13 — Limit sets of Hausdorff dimension < 2 geometrically finite

"Solved by Bishop and Jones." — Wikipedia, Thurston's 24 questions, question 13, read 2026-08-14

14 — Cannon–Thurston maps

"Solved by Mahan Mj." — Wikipedia, Thurston's 24 questions, question 14, read 2026-08-14

15 — Residual separability of f.g. subgroups in f.g. Kleinian groups

"Solved by Ian Agol, building on work of Wise." — Wikipedia, Thurston's 24 questions, question 15, read 2026-08-14

16 — Virtually Haken conjecture

"Solved by Ian Agol." — Wikipedia, Thurston's 24 questions, question 16, read 2026-08-14

17 — Finite cover with positive first Betti number

"Solved by Ian Agol." — Wikipedia, Thurston's 24 questions, question 17, read 2026-08-14

18 — Virtually fibered conjecture

"Solved by Ian Agol." — Wikipedia, Thurston's 24 questions, question 18, read 2026-08-14

20 — Software for surface diffeomorphisms / laminations

"Addressed through development of SnapPea and other software." — Wikipedia, Thurston's 24 questions, question 20, read 2026-08-14

21 — Software to compute hyperbolic structures

"Addressed through development of SnapPea and other software." — Wikipedia, Thurston's 24 questions, question 21, read 2026-08-14

22 — Software tabulating 3-manifold invariants

"Addressed through development of SnapPea and other software." — Wikipedia, Thurston's 24 questions, question 22, read 2026-08-14

24 — Hyperbolic structures at given Heegaard genus

"Solved by Namazi and Souto." — Wikipedia, Thurston's 24 questions, question 24, read 2026-08-14

Method

The rows are transcribed by hand from the consensus ledger named in the source column, cross-checked against Agol's public status note, so there is no fetch.py in this folder. There is no machine-readable upstream: the status of a question in geometric topology is a judgment in the literature rather than a feed. The two dating conventions — span ends for rows 4, 5 and 14, a conventional 2000 for the software rows 20–22 — are stated in the Definition and carried in the rows' notes.

figure.py calls the shared problem_list_chart() in ../../lib/families.py, which keeps the rows whose status is resolved with a non-empty resolved_year and counts resolution events by year from the 1982 list_year to the present. No ai_problem argument is passed, because no row carries an AI credit. The cumulative view is the shared ledger_remaining_chart(). check.py recomputes the fact lines and the register entries from the CSV.

Limitations

AI attribution

No row in thurston-questions.csv names an AI system in its resolver or notes columns; the most recent dated resolution is 2013. No AI credit appears in the Wikipedia table the rows are scored from as of the 2026-08-14 read.

Sources