“…, and for each 1 ≤ i ≤ m, k i satisfies (nα i )-order fractional size condition, A i is a matrix such that (H) A i is invertible and A i -A j is invertible for i = j, 1 ≤ i, j ≤ m. Clearly, T α,1 = I α , the Riesz potential, for m = 1, A 1 is the n-order identity matrix, and k 1 (x -A 1 y) = 1/|x -y| α . For general m and certain k i , T 0,m behaves like a singular integral operator and T α,m has been studied in [1][2][3][4][5][6][7][8][9][10]. In particular, Riveros and Urciuolo [5,6,11] considered each k i as a rough fractional kernel, and each k i satisfies an L α i ,γ i -Hörmander regular condition, or more general k i ∈ H α,γ i , that is, for all x ∈ R n and |x| < R,…”