T

leonarski_fandClaude Opus 5.5 a628f06868 Space-group search: an ask that promotes over a twin-gate refusal is decided by the twin-immune zone

Open set 5ebi (deposited P2_1, a = c and beta = 120: a monoclinic crystal on a hexagonal metric,
pseudo-merohedrally twinned, <|L|> 0.433) regressed from P2_1 to C222_1 with dq-sm2-rest baf2017c9.
Of that commit's two changes it is the sub-lattice ask's R-contrast operator test, not the hot-patch
mask: 5ebi is a CCD (.img) sweep, so HotPixelFinder never runs on it. Without the R contrast every
metric two-fold that passes min_operator_cc was kept, LePage closed them into the whole hexagonal
metric and no sub-lattice ask was made. With it the false hexagonal two-folds drop out, the two
in-plane two-folds of the C-centred orthohexagonal cell survive (CC 0.97, R 0.061 against 0.045 for
the genuine screw: contrast 0.96), and the ask on that sub-lattice adopted C222_1. The main search
had refused 622 on the added-operator R (contrast 0.70 against 0.72), but the ask's own search
cannot see that: the gates there are relative and the twin law passes them on its own. Stage A's
L-test-under-merge gate does not reach it either - C222_1 is not holohedral on a hexagonal metric -
and read per operator it does not separate it: merging under the in-plane two-fold moves <|L|> only
0.425 -> 0.418 (14% of the gap to 0.375).

Fix: where a twin gate of the search in hand refused a higher group, an ask that would promote
re-opens what that gate answered, so it is arbitrated as every other promotion over a refusal is -
by TwinZoneVerdict on the operators it adds over the group in hand (that group carried into the
ask's setting). Acentric with margin and the group in hand stands. 5ebi: zone 222 over 2,
n 1865, calibrated -23.9 nats -> twin law, P 1 21 1 kept. cuhf2 (the case baf2017c9 fixed) has no
twin-gate refusal in hand, so its zone is not read and P422 stands.

Targeted battery vs the rc174-all2 full run (20261004-2350_f64f76_all2-full), same base:
reg4-v1 (32 sets: 5ebi, cuhf2, sub-lattice sets 6iu6 6iu8 6iu9 6z8o 8t7r 9ea5, twinned/pseudo-
merohedral 9hnc 3meb 2wnn 2xfw 2wnz 4bwl 2wnq insu_H_x06da_twin, controls lyso_x06da_ref
thau_x10sa_0p1deg 5reo, all 14 small-molecule sets): only 5ebi changes - C2221 -> P1211 (pass),
ISa 10.9 -> 14.8, R_meas 12.3% -> 10.2%, R_free (deposited model) 0.571 -> 0.537, cell dev 40% ->
0.05%. Every other set identical in space group, ISa, R_meas, R_free, d_min and SHELXL R1.
reg4-v1b (the 12 other open/in-house sets whose run adopts a metric or sub-lattice ask): identical.
Private arm (the 7 sets whose mask changed with baf2017c9 and the 4 that take an ask): identical.
Still failing as before: 4bwl, 2wnq (near-perfect twins, C222_1 via the metric ask with no refusal
in hand), 6iu9, 9hnc, kdp.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K5K8jvPPbmCrbqnWkddTuB

2026-10-05 09:06:16 +02:00