Folding sequences

M. J. Dunwoody

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arXiv · math/9810192

Folding sequences

M. J. Dunwoody

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Abstract

Bestvina and Feighn showed that a morphism S --> T between two simplicial trees that commutes with the action of a group G can be written as a product of elementary folding operations. Here a more general morphism between simplicial trees is considered, which allow different groups to act on S and T. It is shown that these morphisms can again be written as a product of elementary operations: the Bestvina-Feighn folds plus the so-called `vertex morphisms'. Applications of this theory are presented. Limits of infinite folding sequences are considered. One application is that a finitely generated inaccessible group must contain an infinite torsion subgroup.

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BibTeX RIS

M. J. Dunwoody. 1998-10-26. Folding sequences. https://arxiv.org/abs/math/9810192

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