Where a twin hypothesis (<prefix>_twin_<SG>) was written, the model is also
validated against that merge: as merged, and as twinned by its law -
|F_twin(h)|^2 = (1-a)|F_model(h)|^2 + a|F_model(Th)|^2 from the placed, scaled
model, one overall scale refitted per a, a scanned 0..0.5 on the working set
and R-free read at it (ValidateAgainstModel's new twin_law argument; GPU
structure factors as before). The maps and the placed model are then written
from whichever merge has the lower R-free; the report gives MAPS_FROM and the
subgroup's plain and twinned R-work/R-free and fraction. The subgroup file
follows its own validation's indexing, as the answer follows its own.
The model chooses the maps only: the space group, <prefix>.mtz and R_FREE stay
the answer's. Documented in RUGNUX_REPORT.md, RUGNUX_ADVANCED.md and
CPU_DATA_ANALYSIS_DECISIONS.md (14.9); Yeates (1997) credited.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SVmAWnzCmRKAXVUCdc4iNi
leonarski_fandClaude Opus 5.5
8442d55f6f