Geometry & Topology, Vol. 2 (1998) Paper no. 2, pages 11--29.

The Symmetry of Intersection Numbers in Group Theory

Peter Scott

Abstract. For suitable subgroups of a finitely generated group, we define the intersection number of one subgroup with another subgroup and show that this number is symmetric. We also give an interpretation of this number.

Note: there is a correction to this paper which should be read alongside the paper.

Keywords. Ends, amalgamated free products, trees

AMS subject classification. Primary: 20F32. Secondary: 20E06, 20E07, 20E08, 57M07.

DOI: 10.2140/gt.1998.2.11

E-print: arXiv:math.GT/9712212

Submitted to GT on 21 February 1997. (Revised 13 March 1998.) Paper accepted 19 March 1998. Paper published 19 March 1998.


Notes on file formats

Peter Scott
Mathematics Department University of Michigan Ann Arbor, MI 48109, USA

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