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countermove promotion, retired hung-piece-escape and NumLeftoverMovesToSelect.
Full session was built on a "measure the pick, not the game" methodology:
aggregate solve counts on curated suites are too noisy to tune move-ordering
knobs against, so most decisions here came from per-move fail-high/alpha-raise
rates at much larger sample sizes (leftover FH% instrumentation, a zero-
selection-budget diagnostic that isolates a single best-of-remaining pick,
and evidence-bucket calibration), not solve-count deltas alone. See
CLAUDE.md's "Dynamic move ordering experiments" section for the reusable
methodology and generate.c's _ScoreAllMoves comment for the resulting
ordering hierarchy.
Changes:
- Added g_ContinuationHistory: same growth/decay math as the existing
g_HistoryCounters butterfly table, additionally keyed by the previous
move, so its magnitude is self-calibrated rather than a hand-picked
constant. Flat, sufficient response across a 256x scale sweep.
- Countermove-table matches now get a real GOOD_MOVE-tier promotion
(previously the table was write-only, tracked for stats but never read
for ordering), but only when the match's own accumulated
history+continuation evidence clears COUNTERMOVE_EVIDENCE_THRESHOLD
(10,000) -- a raw match with no track record was shown to perform
identically to an ordinary leftover (~0.6-0.85% FH), so promoting on
match alone would have repeated hung-piece-escape's mistake below.
- Retired hung-piece-escape's unconditional GOOD_MOVE-tier promotion.
Evidence-calibration showed the overwhelming majority of triggers (a
zero-evidence population 250-1000x larger than countermove's) performed
at the plain-leftover baseline -- the promotion was mostly free tier-
escape treatment for moves that hadn't earned it. Replaced with
FLEE_BONUS, a flat same-tier nudge inside SelectBestWithHistory (never
escapes GOOD_MOVE/leftover classification, unlike a generation-time
promotion) at the magnitude found to plateau a same-tier-nudge sweep.
- Retired NumLeftoverMovesToSelect (the depth-indexed budget on how many
leftover moves got a full selection scan before falling back to
unsorted order). search.c's main move loop now always fully selects --
the leftover pool was shown to contain real, findable signal a bailout
budget was discarding for a node-count savings that didn't hold up net-
net once measured by solve counts and fail-high rates rather than raw
node counts (noisy on small suites independent of this change).
- Collapsed leftover-move instrumentation from sorted/raw pairs down to a
single set now that "raw" (unsorted fallback) is structurally
impossible; kept the countermove evidence-bucket calibration counters
(ongoing check that COUNTERMOVE_EVIDENCE_THRESHOLD stays well-
calibrated); removed the contested-node A/B harness and hung-piece
evidence calibration now that the decisions they were built to inform
are made.
Net effect on the three curated suites (sd 10): solve counts wash (tied,
+1, -1 across ringers/confident/hard), leftover fail-high rate improved
consistently on all three (the intended, directly-measured target of this
work). Not yet validated beyond sd 10 -- an sn-based run or
eval_tune/match_play.py head-to-head gate is the natural next check before
leaning on this as a proven strength gain rather than a directionally-
sound, sd-10-clean change.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_014XePz6Sk4qQsTaP2jVJWJu
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EBF/beta-cutoff/counter-move stats, script.c FPE fix.
No LMR, no counter-move-driven move ordering (both explored separately,
kept out for now -- counter-move measured worse, ~655->647 solved on
ecm879 @ sn=4M with a leaner tree beforehand). Futility pruning restored.
Verified: 647/879 solved, EBF 4.609 @ sn=4M; 684/879 solved, EBF 3.995
@ 20s/move, 1cpu, 256m hash (typhoon_baseline.log).
The counter-move table is still written and its stats still tracked
(dynamic.c) for diagnostic purposes, but generate.c no longer reads it
for move ordering, so it has no effect on search behavior in this
commit.
lmr_testing/ holds the in-flight graded-LMR + counter-move code (not
applied here) with notes on what was already tried and measured, so a
future session can resume without re-deriving it.
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