Probability measures on fractal curves (probability distributions on the Vicsek fractal).

In this paper we study the structural, topological, metric and fractal properties of the distribution of the complex-valued random variable ζ = Σ∞k=1 2/3k εηk ≡ Δη1…ηk…, where the indices ηk are independent random variables taking the values 0, 1, 2, 3, 4 with probabilities p0k, p1k, p2k, p3k, p4k respectively, pik ≥ 0, Σ4i=0 pik = 1, Σ4i=0 pik = 1 for any k ∊ ℕ, εm = emπi/2 = im (m = 0, 1, 2, 3) are 4th roots of unity, ε4 = 0. We prove that the distribution of ζ is supported on a self-similar fractal curve such that the branching index of every point is equal to 2 or 4. We obtain conditions for the distribution of ζ to be of pure type: discrete or singularly continuous with respect to two-dimensional Lebesgue measure. In the case of discrete distribution, the point spectrum is described. In the case of singular distribution, we describe topological, metric and fractal properties of minimal closed support (spectrum). We study in detail the case of identically distributed indices. In particular, the mathematical expectation and variance of the random variable are found. [ABSTRACT FROM AUTHOR]