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On the Exponent of Cohomology of Discrete Groups
Author(s) -
Adem Alejandro
Publication year - 1989
Publication title -
bulletin of the london mathematical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.396
H-Index - 48
eISSN - 1469-2120
pISSN - 0024-6093
DOI - 10.1112/blms/21.6.585
Subject(s) - exponent , mathematics , citation , cohomology , algebra over a field , mathematics education , computer science , library science , pure mathematics , linguistics , philosophy
In sufficiently high dimensions, Farrell cohomology coincides with ordinary cohomology. The torsion occurring asymptotically often arises from the finite subgroups in a simple way, but our example shows that a different type of cohomological twisting can appear, linked to the geometry of the singular set of the (j-complex X/V. We obtain a general bound on the exponent of H*(T, Z) by combining the description given previously with a recent result on torsion in equivariant cohomology: