THE COHOMOLOGY RING OF AN HNN EXTENSION OF COMBINATORIALLY ASPHERICAL GROUPS

[摘要] An HNN extension H of a combinatorially aspherical group is shown to have period 2l after three steps if a specific positive integer l may be derived from the associated subgroup monomorphisms. If l > 1 the periodicity is characterised by cup product. Consequently a finite presentation may be found for the cohomology ring of any finitely presented H with trivial coefficients in a principal ideal domain.

[发布日期] 1991-07-01