Abstract
Let \(\alpha\in (-1/2,\infty )\) and let \(\chi _r\) denote the indicator function of the segment \([-r,r]\) . We obtain new two-radii theorems for the Besselconvolution operator \(f\rightarrow f\overset {\alpha }\star \chi _r\) that are related to quasi-analytic classes offunctions. We establish a local analog of the two-radii theorem for functions \(f\) that satisfy the convolution inequalities \(f\overset{\alpha }\star \chi _{r_1}\geq 0\) and \(f\overset{\alpha }\star \chi _{r_2}\leq 0\) . We alsopresent applications of these results to uniqueness theorems for solutions of the Cauchy problemfor the generalized Euler–Poisson–Darboux equation and to closure theorems for generalizedshifts.