From: OsherD on 1 May 2010 01:41 From Osher Doctorow The "needed" 3-dimensional generalization of Catalan Numbers are Fuss- Catalan Numbers, defined by J. - C. Aval of U. Bordeaux France (and others) in "Multivariate Fuss-Catalan numbers," arXiv: 0711.0906 v1 [math.CO] 6 Nov 2007, 12 pages, by: 1) C_p(n) or Cp(n) = 1/[(p - 1)n + 1] C(pn, n) where C(pn, n) = number of unordered combinations of n things chosen from pn things. These for p = 3 count ternary trees, which are trees such that every internal node has exactly 3 children, and have 3-dimensional tetrahedron interpretations analogous to 2-dimension Catalan number triangle interpretations and similarly for their corresponding arrays. We have: 2) C3(n) = [1/(n + 1)] C(3n, 3) It turns out that just as Catalan numbers are sums of "ballot numbers" in 2 dimensions, so Fuss-Catalan numbers are sums of "ballot numbers" in 3 dimensions, where the 2-dimensional ballot number B(n, k) is: 3) B(n, k) = [(n - k)/(n + k)]C(n + k, n) and: 4) C(n) [nth Catalan number] = sum B(n, k) where sum is for k = 0 to n - 1. For 3-dimensional ballot numbers B3(n, k, L): 5) B3(1, 0, 0) = 1, B3(n, k, L) for n > 1 and k + L < n is sum B3(n - 1, i, j) where sum is over: 6) 0 < = i < = k, 0 < = j < = L We have analogous to (4): 7) C3(n) = {1/[2n + 1]}C(3n, n) = sum B3(n, k, L) where sum is over k and L, n integer < = 0. The quantities B3(n, k, L) also have an explicit equation: 8) B3(n, k, L) = C(n+k, k)C(n+L-1, L) [n-k-1]/[n+k] Notice in (8) the appearance of n - k - 1 which is -(1 + y - x) for y = k, x = n, where 1 + y - x is the usual Probable Causation/Influence provided that the integers are normalized (roughly speaking, divided by a constant integer larger than all of them). This type of thing occurs also in equation (1) in the denominator. Osher Doctorow
From: OsherD on 1 May 2010 01:47 From Osher Doctorow Regarding (5), I should mention also that B3(n, k, L) = 0 if k + L > = n. J. - C. Aval has 22 papers in arXiv, 2001 through 2009. Osher Doctorow
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