arXiv math/03031312003-03-11math.GRmath.DG

Tits alternative for closed real analytic 4-manifolds of nonpositive curvature

Xiangdong Xie

备注：: 26 pages

英文摘要：

We study subgroups of fundamental groups of real analytic closed 4-manifolds with nonpositive sectional curvature. In particular, we are interested in the following question: if a subgroup of the fundamental group is not virtually free abelian, does it contain a free group of rank two ? The technique involves the theory of general metric spaces of nonpositive curvature.

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