Semi-Strongly solved: a New Definition Leading Computer to Perfect Gameplay

Fuente: arXiv
Saved in:
Bibliographic Details
Main Author: Takizawa, Hiroki
Format: Preprint
Published: 2024
Subjects:
Online Access:
Tags: Add Tag
No Tags, Be the first to tag this record!
_version_ 1866910072698830848
author Takizawa, Hiroki
author_facet Takizawa, Hiroki
contents Strong solving of perfect-information games certifies optimal play from every reachable position, but the required state-space coverage is often prohibitive. Weak solving is far cheaper, yet it certifies correctness only at the initial position and provides no formal guarantee for optimal responses after arbitrary deviations. We define semi-strong solving, an intermediate notion that certifies correctness on a certified region R: positions reachable from the initial position under the explicit assumption that at least one player follows an optimal policy while the opponent may play arbitrarily. A fixed tie-breaking rule among optimal moves makes the target deterministic. We propose reopening alpha-beta, a node-kind-aware Principal Variation Search/Negascout scheme that enforces full-window search only where semi-strong certification requires exact values and a canonical optimal action, while using null-window refutations and standard cut/all reasoning elsewhere. The framework exports a deployable solution artifact and, when desired, a proof certificate for third-party verification. Under standard idealizations, we bound node expansions by O(d b^(d/2)). On 6x6 Othello (score-valued utility), we compute a semi-strong solution artifact supporting exact value queries on R and canonical move selection. An attempted strong enumeration exhausts storage after exceeding 4x10^12 distinct rule-reachable positions. On 7x6 Connect Four (win/draw/loss utility), an oracle-value experiment shows that semi-strong certification is 9,074x smaller than a published strong baseline under matched counting conventions. Semi-strong solving provides an assumption-scoped, verifiable optimality guarantee that bridges weak and strong solving and enables explicit resource-guarantee trade-offs.
format Preprint
id arxiv_https___arxiv_org_abs_2411_01029
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Semi-Strongly solved: a New Definition Leading Computer to Perfect Gameplay
Takizawa, Hiroki
Artificial Intelligence
Strong solving of perfect-information games certifies optimal play from every reachable position, but the required state-space coverage is often prohibitive. Weak solving is far cheaper, yet it certifies correctness only at the initial position and provides no formal guarantee for optimal responses after arbitrary deviations. We define semi-strong solving, an intermediate notion that certifies correctness on a certified region R: positions reachable from the initial position under the explicit assumption that at least one player follows an optimal policy while the opponent may play arbitrarily. A fixed tie-breaking rule among optimal moves makes the target deterministic. We propose reopening alpha-beta, a node-kind-aware Principal Variation Search/Negascout scheme that enforces full-window search only where semi-strong certification requires exact values and a canonical optimal action, while using null-window refutations and standard cut/all reasoning elsewhere. The framework exports a deployable solution artifact and, when desired, a proof certificate for third-party verification. Under standard idealizations, we bound node expansions by O(d b^(d/2)). On 6x6 Othello (score-valued utility), we compute a semi-strong solution artifact supporting exact value queries on R and canonical move selection. An attempted strong enumeration exhausts storage after exceeding 4x10^12 distinct rule-reachable positions. On 7x6 Connect Four (win/draw/loss utility), an oracle-value experiment shows that semi-strong certification is 9,074x smaller than a published strong baseline under matched counting conventions. Semi-strong solving provides an assumption-scoped, verifiable optimality guarantee that bridges weak and strong solving and enables explicit resource-guarantee trade-offs.
title Semi-Strongly solved: a New Definition Leading Computer to Perfect Gameplay
topic Artificial Intelligence
url https://arxiv.org/abs/2411.01029