The Original I Ching
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T · 易 · the z-transform of the count

The transfer matrix: design your rule

Choose which lines may sit together, and count

Choose which line adjacencies you allow and look at the matrix, its powers, the counts and its dominant eigenvalue.

The Fibonacci in the hexagram experiment was one case: forbidding two adjacent yin. Here you choose which adjacencies you allow, with a 2x2 matrix M where M[a][b] = 1 if line b may sit above a. Its powers count the figures by number of lines (1ᵀMⁿ⁻¹1), its trace the cyclic ones, and its dominant eigenvalue is the growth ratio. It is the z-transform of the count; Laplace's does not apply, because the I Ching has no continuous time: the honest no beside the discrete yes.

touch a cell: may b sit above a?
yinyang
yin
yang
figures by number of lines (n = 1..6)
2
1
3
2
5
3
8
4
13
5
21
6
cyclic (trace) n = 2..6: 3, 4, 7, 11, 18
2 3 5 8 13 21
sequence of counts
1.6180
dominant eigenvalue (growth)
21
valid hexagrams (6 lines)
18
valid on a ring
A special case: the Catalan paths

Outside the adjacency rules there is another famous count hidden: the balanced hexagrams (3 yang, 3 yin) where, reading from the bottom up, yang never falls behind yin. They are the Dyck paths, and there are exactly C3 = 5.

63
55
60
54
11

the 5 Catalan hexagrams: 42, 44, 50, 52, 56