Beta release. Problem Forge is new and open by invitation. The beta test period runs through 2026-11-30; the full opening is on 2026-12-01 00:00 UTC. Things may break, and we may correct the boards when they do. The difficulty of some rungs may be wrong. There are no prizes during the beta, and the bounty is not open. Your account and your progress stay when the beta ends. Please tell us what goes well and what goes wrong: admin@problemforge.com.

The 10 problems

Every rung of the ten problems has exactly one solution.

Each page below explains its problem with 3 examples. Start with any one.

Check an answer · References · On using AI