Alphabeta Math
AlgorithmAlgorithm: Literature-sourcedProof: Not applicablePipeline-generated
How statement and proof provenance work

The first chip identifies the source of the statement or construction; the second identifies the source of its local proof or verification.

  • Literature-sourced: the exact statement appears in a cited source; only wording and notation differ.
  • AI-adapted: a semantically identical restatement of literature-sourced material, modulo indexing, notation, and boundary cases adopted by the library.
  • AI-generated: a genuinely novel statement formulated by AI, with no source for the claim itself.

These labels describe origin, not correctness: citations and verification chips remain separate evidence.

Extended value iteration for a confidence set

Definition

Input finite nonempty state and action sets, upper reward estimates r~(s,a), empirical transition laws P^(⋅∣s,a), nonnegative transition radii bp(s,a), a tolerance ε>0, and fixed orders of the states and actions for tie-breaking. For a vector v∈RS, write span⁡(v)=max⁡sv(s)−min⁡sv(s) and let Δ(S) be the probability simplex on S. Initialize u0(s)=0. At iteration i≥1, compute ui(s)=max⁡a∈A(s)[r~(s,a)+max⁡q∈Δ(S):∥q−P^(⋅∣s,a)∥1≤bp(s,a)q⋅ui−1]. For every state-action pair (s,a), run the following transfer routine using v=ui−1. Put q=P^(⋅∣s,a), c=min⁡{1,bp(s,a)/2}, and order the states x1,…,xm by nondecreasing v(xj), using the fixed state order to break ties. Set j=1 and ℓ=m. While c>0 and j<ℓ, advance j while q(xj)=0, then decrease ℓ while j<ℓ and q(xℓ)=1. If j≥ℓ, stop. If v(xj)≥v(xℓ), stop. Otherwise set d=min⁡{c,q(xj),1−q(xℓ)}, replace q(xj) by q(xj)−d and q(xℓ) by q(xℓ)+d, and replace c by c−d; repeat. Call the resulting vector qi,s,a.

For each state, compute Bi(s,a)=r~(s,a)+qi,s,a⋅ui−1 for every action, record the first action ai(s) in the fixed action order attaining max⁡a∈A(s)Bi(s,a), and set qi(⋅∣s)=qi,s,ai(s). If span⁡(ui−ui−1)<ε, return the stationary deterministic policy πi(s)=ai(s), its corresponding transition rows qi, the vector ui−1 used in that backup, and the iteration index. Otherwise continue. The procedure is partial unless a separate termination result applies.

Definition references

Bounded-reward finite MDP: provides the finite state/action sets and reward/transition laws.

EVI correctness and termination: proves that the transfer routine returns the exact row maximum and that positive radii give finite termination.

UCRL2 Extended Value Iteration: §3.1.2, Figure 2 and equation (5).

Average-reward value iteration discussion: Chapter 7, §§7.3–7.4.

Depends on

Used by

Dependency tree · two levels

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Sources