Why we pivoted then
F8.1 is closed for 2x2 and blocked for 3x3. F5 is tenth in the ranking, after F8; the ranking is unchanged.
What happened before
- 0193: error. The first launch died with the shell it was started from, and the relaunch stopped on a pickling error in the worker pool.
- 0194: Hill 2x2 with the letters numbered in any order. The known words give 22 equations, a few bits more than the unknowns, so the test can decide. Every invertible matrix was checked at both pairings: none fits K4 or a scrambled copy under any numbering, and planted texts each fit only their own matrix.
- Hill 3x3 with a free numbering is 21-32 bits short of a single check: blocked.
The change we believe is needed
- F5 next: F5.2 (three-term rules on a free alphabet in bases other than 10, and longer two-term lags), then F5.1 (multiplicative feedback; YAR as a primer).
- Then F9, the last family before the stopping point.