Certain residual properties of HNN-extensions with normal associated subgroups

E. V. Sokolov, E. A. Tumanova

Let $\mathbb{E}$ be the HNN-extension of a group $B$ with subgroups $H$ and $K$ associated according to an isomorphism $\phi :H\to K$. Suppose that $H$ and $K$ are normal in $B$…