Strictly positive definite kernels on subsets of the complex plane (Q936700)

Let \((z,w)\in C \times C\rightarrow f(z\bar{w})\) be a positive definite kernel and \(B\) be a subset of \(C.\) The authors deal with conditions suchthat the restriction \((z,w)\in B\times B\rightarrow f(z\bar{w})\) is strictly positive definite. The problem is a generalization of the case where \(B\) is either \(C\) or the unit circle in \(C\).