Some general thoughts. I really think that we are on the right track. I like the idea of working with the cycles as a group, and the symbols as a group to try to identify characteristics about each so that we can break them down into subgroups. Sort of looking at trees individually, and then looking at groups of trees, and then looking at the forest.
I also think that we may be on the right track with the wildcard hypothesis. I am not emotionally attached to it. I think that the high frequency symbols that do not have cyclical relationships could also be 1:1 substitution or filler. But the more I think about it, the more wildcards makes sense. Zodiac knew about diffusion. Why would he defeat the purpose of using multiple symbols to represent the letters with mid-range count, and then make frequency attack easy for the high count letters? Fillers is a possibility as well.
I have been analyzing the 340 a little bit this morning, here is the table of all higher frequency symbols:
340SummaryTable1.png
Also, here is a simple scatter graph of the analysis, with count on the X axis and total score on the Y axis. Note that if a symbol is in a cycle with other symbols, then their count will be roughly the same. They would cluster together, at least vertically, on the graph. The upper left is a large clustering of mid-range count symbols that have a lot of cycle relationships with each other. On the lower left would be a few low-range count symbols that are probably 1:1 substitution for low frequency letters.
340Scatter.png
Some of the below is redundant, but I wanted to be more thorough today.
The proposed wildcards are in red. They are high in count and do not have strong cycle relationships with other symbols.
5 has some cycling with 29 (5 5 29 5 5 5 5 29 5 29 5 29 5 29 5 29 5). Score 59%.
51 has some cycling with 23 (23 23 51 51 23 51 23 51 23 51 23 51 51 51 23 51 23 51 23 23). Score 55%.
51 has some cycling with 36 (36 51 51 51 36 51 36 51 36 51 51 36 51 36 36 36 51 36 51 36). Score 50%.
Part of my analysis is a little bit subjective. You could flip a coin all day long and get patterns like these of which there are thousands.
But see the Alternative Possibilities for 11, 23, 36, and 51 below.
Note
26 and 50 (purple) have counts of 6 and 7, but have little or no cycle relationships. all of the other symbols of that count are in cycles, but these are not.That's what separates them out as a group. They are either 1:1, wildcards or filler. I am suggesting that they could represent low frequency letters. Zodiac didn't feel the need to put them in cycles, but they appear in higher frequency than Zodiac anticipated because of his choice of words. Thus, they set apart from the other symbols.
Symbols
16 and 40 (blue) are in a strong cycle together (16 40 16 40 16 16 40 16 40 16 40 16 40 16 40 16 16 40 40), however I learned with Experiment 3 J-ST that this can happen quite by chance, and be a false cycle. Or they could simply represent a letter with a 19 count as a two symbol cycle. 16 and 40 do have some weak to medium cycling with other symbols, and I don't know what to make of this. I am hoping that they are not cycled wildcards because of their count, but have considered that possibility.
Symbols
11 and 36 (black) cycle fairly strong together (11 36 11 36 11 36 11 36 11 11 36 36 11 36 36 11 36 11 36 11), and the analysis is the same as above. They both cycle weak to medium with several other symbols.
Symbol
23 (green) cycles with several other symbols, including:
with 31 (23 31 23 31 23 31 23 31 23 31 23 31 23 23 23 23 31). Score 65%, could be random.
and 37 (23 37 23 37 23 23 37 23 37 23 37 23 37 23 23 37 23). Score 65%, could be random.
and 51 ((23 23 51 51 23 51 23 51 23 51 23 51 51 51 23 51 23 51 23 23). Score 55%.
Symbols
3, 6, 7, 21, 30 and 31 (orange) mostly all have cycles with each other.
Alternative Possibilities for 11, 23, 36, and 5111, 23, 36 and 51 all have the same count of 10, so theoretically there could be combinations of these symbols in cycles where Zodiac made symbol choices at random,
which could exclude 51 from the group of proposed wildcards. Here are some possibilities:
340.11.23.36.56.png
ConclusionSymbols 5, 19 and 20 are still the best candidates for wildcards, because they do not cycle with each other or any other symbol well. However, I now think Symbol 51 could possibly be in a cycle with Symbol 23 and represent the same letter. If that is the case, then Zodiac could have used only a few symbols to represent high frequency letters.
I would have to put 51 in a borderline category.
S.T.