The arithmetic of the characteristic Pólya functions

A. I. Il'inskii

Matematičeskie zametki, Tome 21 (1977) no. 5, pp. 717-725

Résumé

In the framework of the theory of D. Kendall's delphic semigroups are considered problems of divisibility in the semigroup pgr of convex characteristic functions on the semiaxis $(0,\infty)$. $N(\pi)=\{\varphi\in\pi:\varphi_1\mid\varphi\Rightarrow\varphi_1\equiv1\text{ or }\varphi_1=\varphi\}$ and $I_0(\pi)=\{\varphi\in\pi:\varphi_1\mid\varphi\Rightarrow\varphi_1\notin N(\pi)\}$. The following results are proved: 1) The semigroup pgr is almost delphic in the sense of R. Davidson. 2) $N(\pi)$ is a set of the type $G_\delta$ which is dense in $\pi$ (in the topology of uniform convergence on compacta). 3) The class $I_0(\pi)$ contains only the function identically equal to one.