Why we pivoted then
Family 1 was re-entered for four experiments (0009-0012) and came out bounded for periodic, progressive and autokey keys under every alphabet the puzzle's vocabulary could build. Nothing in it was left that the known letters could decide cheaply.
What happened before
- 0009 and 0010 read the key letters forced by EASTNORTHEAST and BERLINCLOCK as English, under the standard, KRYPTOS and 248 vocabulary-mixed alphabets: the best stretch equals the best from scrambled copies.
- 0011 ruled out the progressive key at periods 1-25 and 31-51 at every step.
- 0012 chained plaintext autokey from the known letters: lags 1-25 and 30-52 dead, 26-29 force noise.
The change we believed was needed
The known letters force 13 and 11 consecutive key shifts. If those shifts were digits from a number stream that feeds on itself, a Gromark-style recurrence, the stream would show it directly. That is cheap to test and needs no word list (0013).