Motivation
Mean-payoff games ask which starting positions allow a player to guarantee a nonnegative long-run average reward. Binary-encoded weights make the bit cost of solving the complete winning set a central part of the question. The source manuscript presents the surrounding research claim.
Setting
A game is a finite nonempty directed multigraph with integer edge weights, an owner for each vertex and an outgoing edge everywhere. Winning means that a history-dependent maximizer strategy guarantees liminf average payoff at least zero against every opponent strategy.
Formalization target
Construct one randomized three-tape machine and C>0 such that every encoded game of length L has a time bound
T≤2C(log2(L+2))2,
all T-bit random tapes halt by T, and at least 7/8 of them output the exact winning-set indicator, with all other output cells blank.
The selected formal target is OAI.randomized_quasipolynomial_mean_payoff.
Significance and status
The target makes the input encoding, computation model, success fraction and complete output explicit. It is an existence theorem for a uniform machine, not a separate solver for each game. The published target is currently Open; the manuscript's argument and a checked Lean proof are separate deliverables.
Difficulty
The running time must hold on every random tape, while correctness holds on the specified fraction. Signed weights and the full binary input length cannot be replaced by unary magnitude bounds.
Formalization scope
The published definitions specify games, strategies, plays, liminf payoffs, serialization and tape transitions. The independent finite Truffet elimination counterexample is retained as contextual reference; it is not a prerequisite or an asserted proof of the randomized algorithm. The manuscript’s certification/always-correct consequence is not an additional attached goal.
Selected references
- OpenAI, Randomized quasipolynomial-time mean-payoff games, preprint, 2026. Pinned manuscript.
- OpenAI, accompanying formal statements, commit
adc7f1241b42. Goal source.