On cyclic variation-diminishing transforms
The authors give a new and more manageable characterization for Cyclic Pólya Frequency (CPF) functions of order 3. Their theorems also improve some known results concerning smoothness properties in CPF. Furthermore, a conjecture of Mairhuber, Schoenberg and Williamson about discontinuous CPF functions is also proved.
scientific article; zbMATH DE number 645055