“…Due to the homothetic structure of our operators, it seems that the most natural way to frame the theory is to work with the Haar measure in R N + , i.e., µ(A) := A t −1 dt, where A is a Borel subset of R N + . Results about homothetictype operators in various settings can be found, for example, in [19,32,44,18,39,17,15,16,3,10,11,12], while for similar results about classical convolution operators see, e.g., [23,41,33,14,20,6,7,8,2,4].…”