“Gromark with any mixed alphabet at all, not just ones built from the puzzle's words”
Experiments 13, 28, 46 and 54 tested the Gromark running-number key only on alphabets built from the puzzle's words. Here the mixed alphabet is left completely free: the 24 known letters must fit some one-to-one alphabet, which the run checks exactly for every starting number and every two-term rule up to six digits back.
GromarkGromark A cipher whose secret is a short number that grows into a long stream of digits by adding pairs of earlier digits; each message letter is pushed along the alphabet by the next digit. is a cipher whose secret is a short starting number that grows into a long stream of digits, each digit the sum of two earlier ones, plus a scrambled alphabet. Earlier experiments only tried scrambled alphabets built from the puzzle's wordsthe puzzle's words A list of 62 words tied to the sculpture: the earlier secret words, place names, the names of the people involved, the words in the Morse code, and the themes Sanborn has named.. Here the alphabet can be any scramble at all. That sounds hopeless to search, but it is not: the same plain letter must always land on the same carved letter when the digit is the same, which pins the digits down so tightly that every starting number can be checked in a fraction of a second.
Words in the margin are defined on the glossary page.
1.1
The method at work
The carved letters go in at the top; the reading comes out at the bottom.
the cipher
Gromark adds a running stream of digits to the message on a mixed alphabet. The stream starts from a short primer and grows by adding earlier digits.
the check
With the primer 12345, places 26 and 27 both carve Q but land in two different slots of the alphabet: impossible, so this primer is dead whatever the alphabet.
the bound
All 15 two-term rules up to 6 back, every 5-digit primer, four forms, a completely free alphabet: no fit on K4 or on any shuffled copper.
2
Best candidate against the known letters
This experiment produced no candidate: the search ruled everything out before a full text was built. Its product is the bounded negative in section 7.
3
Walkthrough, by hand
Redo the method on a few letters with pencil and paper.
Take Rogers' rule, each digit the sum of the digits five and four places earlier, mod 10, and the primer 1 2 3 4 5.
Places 26 and 27 both carve Q, from known N and O.
With the form M[P + d] = c, N (13) plus the 26th digit (9) gives slot 22, and O (14) plus the 27th digit (7) gives slot 21.
Two different slots of one alphabet cannot both hold Q, so this primer is dead.
Repeat for every primer, rule and form.
the worksheet: the first steps by hand, on squared paper
4
Worked example, generated
The same steps run by the code on the real letters.
Rogers' rule (5 and 4 back), primer 12345
stream 1234535798826760833681694975336286
place known carved digit slot (M[P+d]=c)
22 E F 1 5
23 A L 6 6
26 N Q 9 22
27 O Q 7 21
31 E G 6 10
5
Hypothesis, for a cryptanalyst
Family, key space, the constraint under test, and the clues it reads.
Family 5, free-alphabet Gromark (the open corner named in families.md after 0028 and 0046). Key digits base 10 from a lagged-Fibonacci rule d[i] = d[i-a] + d[i-b] mod 10, 1 <= a < b <= 6 (15 rules, including Rogers' Gromark a = 4, b = 5), every primer of b digits (5,432,200 primers in all). Four forms, with P, C the standard-alphabet indices and M an unknown mixed alphabet: M[P + d] = c, M[P - d] = c, M[C - d] = p, M[C + d] = p (mod 26). For each primer the 24 cribs give slot-letter pairs that must be a partial bijection: equal slots need equal letters and equal letters need equal slots. Because the digits lie in 0-9, every pair of cribs with the same letter fixes an exact digit difference, so most primers die on the first two such pairs; survivors get the full bijection check. Exhaustive for these rules and forms in base 10. Run on K4 and ten shuffled coppers. Clue entries: C22(a) (the raised YAR / DYAHR as a Gromark primer), C4(b) (Scheidt: 'base', a non-standard number system), C5 ('not mathematical' argues against it, recorded).
6
Prediction
Written before the run; the result decides it.
No primer under any of the 15 rules and 4 forms gives a consistent alphabet, on K4 or on any of the ten shuffled coppers. Zero candidates pass.
7
Method
For each rule, generate the digit stream from every primer and keep the digits at the 24 known places.
For each form, list pairs of known places with the same letter; each fixes the difference of their two digits.
Keep primers that meet every such difference, then check the full one-to-one alphabet condition.
Repeat on ten shuffled coppers.
8
Result and bounds
The harness's record: candidates, gates, loss, and the negative result this experiment leaves behind.