Experiment 107

“Gromark with a three-term digit rule and any mixed alphabet at all”

0069 closed two-term Gromark rules on a free alphabet; 0046 tried three-term rules only on alphabets built from the puzzle's words. Here the digit rule is d[i] = d[i-a] + d[i-b] + d[i-c] mod 10 for every 1 <= a < b < c <= 6 (20 rules) and every primer of c digits, with the mixed alphabet left free, tested by 0069's exact digit-difference method.

revertedstatus
experiment 69parents
2 mintime, all phases
0candidates
0/24known letters
unclocked
1

The experiment method

What the method does with the 24 known letters.

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. makes a long stream of key digits from a short starting number, each new digit the sum of earlier ones, and uses a scrambled alphabet. Experiment 69 tried every rule that adds two earlier digits, with any scrambled alphabet, and found nothing. Here each digit is the sum of three earlier ones, every such rule and every starting number up to six digits, again with any scrambled alphabet.

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.

OBKRUOXOGHULBSOLIFBBWEASTNORTHEASTOTWTQSJQSSEKZZWATJKLUDIAWINFBBERLINCLOCKWGDKZXTJCDIGKUHUAUEKCARIN: THE COPPER, ALL 97 LETTERS, THE 24 KNOWN PLACES IN ACCENTa Gromark key: start from 1 2 3 4 5; each new digit is the sum of the digits 1, 3 and 5 places back, mod 10EASTNORTHEASTBERLINCLOCK12345953668982734945759006106730763399802988774945193826382716147997062146the key digit at each place, out to the last known letterplaces 26 and 27 both carve Q: N + 6 is slot 19, O + 1 is slot 15; one alphabet cannot hold Q in two slotsthe mixed alphabet is left free: only such clashes, a letter in two slots or two letters in one, can rule a primer out20 three-term rules x 10,631,000 primers up to six digits x 4 formsprimers with no clash0010the copper: 0ten shuffled coppersthe copperOUT: NO READING; NO PRIMER SURVIVES, ON K4 OR ANY COPPEREASTNORTHEASTBERLINCLOCK
the cipher

Gromark grows a long stream of key digits from a short primer, each digit the sum of earlier ones, and enciphers on a mixed alphabet. Experiment 69 tried every two-term rule; here each digit sums three earlier ones.

the check

With the alphabet free, the test is a clash: Q carved at 26 and 27 from N and O must sit in one slot, but this primer puts them in slots 19 and 15.

the bound

All 20 three-term rules, 10,631,000 primers of up to six digits, four ways of applying the digit: no primer survives on K4, nor on any of ten scrambled coppers.

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.

  1. Take the rule: each digit the sum of the digits 1, 3 and 5 places earlier, mod 10, and the primer 1 2 3 4 5.
  2. Extend the stream to place 74.
  3. Places 26 and 27 both carve Q, from known N and O.
  4. With the form M[P + d] = c, N plus the 26th digit and O plus the 27th digit must be the same slot of the alphabet, since both hold Q.
  5. If not, the primer is dead; repeat for every primer, rule and form.
the worksheet: the first steps by hand, on squared paper
RULE: EACH DIGIT THE SUM OF THE DIGITS 1, 3 AND 5 PLACES EARLIER, MOD 10; PRIMER 1 2 3 4 5112233445569758396106118129138142157163174189194205217225239240250266271280296307313320337346Digit 6 is 5 + 3 + 1 = 9 (places 5, 3 and 1). Place 26 carries 6, place 27 carries 1.Form M[P + d] = c: N (13) + 6 = slot 19; O (14) + 1 = slot 15. Both must hold the carved Q.Two different slots of one alphabet cannot both hold Q: this primer is dead.
4

Worked example, generated

The same steps run by the code on the real letters.

rule: each digit the sum of the digits 1, 3 and 5 places earlier, mod 10; primer 1 2 3 4 5
stream: 1 2 3 4 5 9 5 3 6 6 8 9 8 2 7 3 4 9 4 5 7 5 9 0 0 6 1 0 6 7 3 0 7 6

places 26 and 27 both carve Q, from known N and O; form M[P + d] = c:
  N (13) + digit 6 = slot 19;  O (14) + digit 1 = slot 15
  two different slots of one alphabet cannot both hold Q
5

Hypothesis, for a cryptanalyst

Family, key space, the constraint under test, and the clues it reads.

Family 5's open corner: 'three-term rules with a free alphabet' (families.md). Key digits base 10 from d[i] = d[i-a] + d[i-b] + d[i-c] mod 10, 1 <= a < b < c <= 6, every primer of c digits (10,631,000 primers in all). Four forms as in 0069 (M an unknown mixed alphabet, P and C standard indices): M[P + d] = c, M[P - d] = c, M[C - d] = p, M[C + d] = p. Pairs of known places with the same letter fix exact digit differences (digits are 0-9), then the full partial-bijection check. Exhaustive in base 10 for these rules. C22(a), C4(b). A planted text is recovered. Ten shuffled coppers.

6

Prediction

Written before the run; the result decides it.

No primer under any of the 20 rules and 4 forms is consistent, on K4 or on any shuffled copper. Zero candidates.

7

Method

  1. For each rule, generate the digit stream from every primer and keep the digits at the 24 known places.
  2. For each form, pairs of known places with the same letter fix digit differences; keep primers meeting them.
  3. Check the full one-to-one alphabet condition.
  4. Repeat on ten shuffled coppers.
8

Result and bounds

The harness's record: candidates, gates, loss, and the negative result this experiment leaves behind.

0candidates returned
0passed every gate
0/24known letters, best
–lowest loss
nonechampion before

20 of 20 rules, 10,631,000 primers x 4 forms: K4 consistent primers 0; ten shuffled coppers [0, 0, 0, 0, 0, 0, 0, 0, 0, 0].

What was searched, as the harness recorded it.

family
three-term Gromark, base 10, free mixed alphabet
rules
  1. 1, 2, 3
  2. 1, 2, 4
  3. 1, 3, 4
  4. 2, 3, 4
  5. 1, 2, 5
  6. 1, 3, 5
  7. 2, 3, 5
  8. 1, 4, 5
  9. 2, 4, 5
  10. 3, 4, 5
  11. 1, 2, 6
  12. 1, 3, 6
and 8 more
rules planned
20
primers
10,631,000
forms
M[P+d]=c, M[P-d]=c, M[C-d]=p, M[C+d]=p
k4 consistent
none
k4 count
0
control counts
0, 0, 0, 0, 0, 0, 0, 0, 0, 0

How this experiment sits among the others is on the lineage page; its family's open hypotheses are on the families page.

Rendered from the record on 2026-10-18 12:26 UTC; updated after every experiment.
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