Ideal Analytic sets

Abstract

The aim of this paper is to give natural examples of ${\mathbf{\Sigma }}_1^1$-complete and ${\mathbf{\Pi }}_1^1$-complete sets. In the first part, we consider ideals on $\omega$. In particular, we show that the Hindman ideal $\mathcal{H}$ is ${\mathbf{\Pi }}_1^1$-complete and consider a number of ideals generated in the similar fashion. Moreover, we show that the ideal $\mathcal{D}$ is also ${\mathbf{\Pi }}_1^1$-complete. In the second part, we focus on families of trees (on $\omega$ and $2$) containing a specific tree type. We show the connection between two topics and explore some classical tree types (like Sacks and Miller).

arXiv comment13 pages