Amalgamated free products, unstable homotopy invariance, and the homology of SL_2(Z[t])

dc.creatorKnudson, Kevin P.
dc.date1998-03-27
dc.date.accessioned2026-07-07T05:24:14Z
dc.date.available2026-07-07T05:24:14Z
dc.descriptionWe show that if R is an integral domain with many units, then the inclusion E_2(R) --> E_2(R[t]) induces an isomorphism in integral homology. This is a consequence of the existence of an amalgamated free product decomposition for E_2(R[t]). We also use this decomposition to study the homology of E_2(Z[t]). We show that H_i(E_2(Z[t]),Z) contains a countable rank free summand for each i>0 and that this summand maps nontrivially into H_i(SL_2(Z[t]),Z); hence, the latter is not finitely generated. This improves on a result of Grunewald, et.al., which states that SL_2(Z[t]) has free quotients of countable rank (and hence, H_1(SL_2(Z[t]) is not finitely generated).
dc.description13 pages
dc.identifierhttps://arxiv.org/abs/math/9803139
dc.identifierhttp://arxiv.org/abs/math/9803139
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/76756
dc.subjectK-Theory and Homology
dc.subjectGroup Theory
dc.subject20G10; 19D50
dc.titleAmalgamated free products, unstable homotopy invariance, and the homology of SL_2(Z[t])
dc.typetext

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