A one-entry leaf memo across chance strata is a semantics-preserving speedup of the fast fair-D4 search
Memoising the fast fair leaf's eighteen board-only features across consecutive leaf calls with the same (board, moves_remaining), recomputing only next_disc_vertical_options, produces bit-identical leaf values, identical actions, logical work, nodes, cache hits and completed depth, and reduces the wall time of a depth-4 decision by at least 1.5x at five and seven chance strata.
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Technical recordThe registered claim, mechanism and falsification criteria
- Claim
- Memoising the fast fair leaf's eighteen board-only features across consecutive leaf calls with the same (board, moves_remaining), recomputing only next_disc_vertical_options, produces bit-identical leaf values, identical actions, logical work, nodes, cache hits and completed depth, and reduces the wall time of a depth-4 decision by at least 1.5x at five and seven chance strata.
- Mechanism
- Within one chance node the strata share the post-move board whenever the cascade consumed no reveal draw; only the sampled next disc differs, and fast-leaf.hpp reads next_disc in exactly one term. Identical inputs give identical doubles; the dot product is re-run in the frozen order; the memo sits below the search's work increment so no recorded observable changes (audit-06 and its adversarial review).
- Falsification criteria
- Any leaf-value bit mismatch, any action/work/node/cache-hit/completed-depth mismatch against FastSearch, or any thread-count-dependent result on the probe games: not semantics-preserving.
- Interleaved timing ratio below 1.5x on real roots at either strata setting: the speedup claim is not supported as tested.
- Information class
- engineering
- Lifecycle
- assessed
- Assessment
- supported-as-tested
- Evidence tier
- mechanics-only
- Dependencies
- none recorded
- Evidence references
docs/exploratory/audit-06-engine-efficiency.mdruns/RUN-20260822T072033Z-510cf15e/kimi-k3-audit-review.mdruns/RUN-20260822T073338Z-48e4df54/gates.log
Agent contextHow to extend this record
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Registered by Claude Code / claude-fable-5.