geometry-topology / Geometric group theory; aspherical manifolds and Poincare duality groups

Wall's manifold-realization question for finitely presented Poincare duality groups

Theorem 1.1: there is a finitely presented group GG with a finite oriented four-dimensional aspherical Poincare complex as classifying space, Hi(G;ZG)=0H^i(G;\mathbb ZG)=0 for i≠4i\ne4 and H4(G;ZG)≅ZH^4(G;\mathbb ZG)\cong\mathbb Z with trivial action, such that no closed aspherical topological 4-manifold has fundamental group GG. This answers Wall's question negatively for finitely presented integral PDPD groups with finite classifying space. Not shown: a counterexample in dimension 3 or in dimensions at least 5, or anything about smooth or homology-manifold realizations beyond the topological category.

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geometry-topologySep 24, 2026Significance 42/100Registry: unreviewed

Wall's manifold-realization question for finitely presented Poincare duality groups

Prior state unknown→disproved

Theorem 1.1: there is a finitely presented group GG with a finite oriented four-dimensional aspherical Poincare complex as classifying space, Hi(G;ZG)=0H^i(G;\mathbb ZG)=0 for i≠4i\ne4 and H4(G;ZG)≅ZH^4(G;\mathbb ZG)\cong\mathbb Z with trivial action, such that no closed aspherical topological 4-manifold has fundamental group GG. This answers Wall's question negatively for finitely presented integral PDPD groups with finite classi…

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Theorem 1.1: there is a finitely presented group GG with a finite oriented four-dimensional aspherical Poincare complex as classifying space, Hi(G;ZG)=0H^i(G;\mathbb ZG)=0 for i≠4i\ne4 and H4(G;ZG)≅ZH^4(G;\mathbb ZG)\cong\mathbb Z with trivial action, such that no closed aspherical topological 4-manifold has fundamental group GG. This answers Wall's question negatively for finitely presented integral PDPD groups with finite classifying space. Not shown: a counterexample in dimension 3 or in dimensions at least 5, or anything about smooth or homology-manifold realizations beyond the topological category.

Theorem 1.1: there is a finitely presented group GG with a finite oriented four-dimensional aspherical Poincare complex as classifying space, Hi(G;ZG)=0H^i(G;\mathbb ZG)=0 for i≠4i\ne4 and H4(G;ZG)≅ZH^4(G;\mathbb ZG)\cong\mathbb Z with trivial action, such that no closed aspherical topological 4-manifold has fundamental group GG. This answers Wall's question negatively for finitely presented integral PDPD groups with finite classifying space. Not shown: a counterexample in dimension 3 or in dimensions at least 5, or anything about smooth or homology-manifold realizations beyond the topological category.

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