2025/08/28 by Chen, Jia-Long, Ai, Wen-Hui
#28A80 #42C05 #46C05 #FOS: Mathematics #Functional Analysis (math.FA)
paper · doi:10.48550/arxiv.2508.20809
We investigate the spectral properties of a class of Sierpinski-type self-affine measures defined by μM,D(⋅) = p-1 ∑d ∈ D μM,D(M(⋅) - d), where \( p \) is a prime number, \( M = \beginbmatrix ρ1-1 & c 0 & ρ2-1 \endbmatrix \) is a real upper triangular expanding matrix, and \( D = \d0, d1, ⋯, dp-1\ ⊂ ℤ2 \) satisfying \( Z(\widehatδD) = ∪j=1p-1 ( \fracj \bmap + ℤ2 ) \) for some \( \bma ∈ Ep= \ (i1, i2)^* : i1, i2 ∈ [1, p-1] ∩ ℤ \ \), where \( Z(\widehatδD) \) denotes the set of zeros of \( \widehatδD \) with \( δD = (1)/(# D) ∑d ∈ D δd \). When ρ1 = ρ2, we derive necessary and sufficient conditions for μM,D to both: (i) possess an infinite orthogonal set of exponential functions, and (ii) be a spectral measure. When no infinite orthogonal exponential system exists in L2(μM,D), we quantify the maximum number of orthogonal exponentials and provide precise estimates. For ρ1 ≠ ρ2, with restricted digit sets D, we obtain a necessary and sufficient condition for μM,D to be a spectral measure.