Largo:
Zodiac cycled his homophones when he encoded the 408, and there is evidence of some cycling in the 340 but not as much. I want to know why. I figure he may have used some other patterns besides perfect cycles, but still perfect. Or regional encoding, or perhaps some pattern that causes regional encoding. With 63 symbols I have 1,953 possible combinations of symbols. I use numbers for symbols because it is easier for me. For each of the 1,953 combinations, I delete all symbols in the array that are not the two symbols that I am looking at, and collapse the array. Then convert the symbols to either A's or B's.
The 408 is on the left, the 340 on the right. X axis is count of that pattern found out of all possible symbol combinations. For the 408 the top two were long sequences of consecutive alternations, or perfect cycles. The 408 has more of the longer pattern than any other pattern. The 340 has more combinations with ABABA than anything else, it is a shorter pattern but there a lot of them. Some are not true, some are false. I am wondering about ABAABA and ABAABAA. Since the method worked so well for the 408, I wonder if some of these are actually true patterns, actual letters.
cycle chunks 1.png
To cause regional bias, or the symbols that appear exclusively in the top 6 and bottom 6 rows, I hypothesize that he did encode with regional or semi regional cycles. Moonrock's idea. Something like this: AAABABABABABABABAAA. The A's at the beginning and end would cause the regional bias. I can't divide into equal chunks because there is an odd number of symbols, so I have to take out the middle symbol so I can compare. AAABABABA ABABABAAA. Except that this exact cycle wouldn't cause the A to avoid the middle 8 rows.
HypothesisMaybe he did something like A B C A B C B C B C B C A B C A B C. That would cause the regional bias for A.
If he did the exact same or very similar thing like this with more than one symbol, then maybe we can detect them and find out if they are statistically improbable or not. I am saying that maybe he did this to avoid the long perfect cycles, because with long perfect cycles a person could maybe identify them and use frequency attack. If you applied frequencies, then maybe you could see that the message was transposed. He could have hidden the homophone groups better by just randomly selecting homophones from their groups, but he liked to cycle and use patterns.
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