Semistability of amalgamated products, HNN-extensions, and all one-relator groups

  title={Semistability of amalgamated products, HNN-extensions, and all one-relator groups},
  author={Michael L. Mihalik and Steven T. Tschantz},
  journal={Bulletin of the American Mathematical Society},
The authors announce the following theorem. Theorem 1. If $G=A*_H B$ is an amalgamated product where $A$ and $B$ are finitely presented and semistable at infinity, and $H$ is finitely generated, then $G$ is semistable at infinity. If $G=A*_H$ is an HNN-extension where $A$ is finitely presented and semistable at infinity, and $H$ is finitely generated, then $G$ is semistable at infinity. 

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