No CrossRef data available.
Published online by Cambridge University Press: 21 April 2025
We show that the fundamental groups of smooth $4$-manifolds that admit geometric decompositions in the sense of Thurston have asymptotic dimension at most four, and equal to four when aspherical. We also show that closed
$3$-manifold groups have asymptotic dimension at most three. Our proof method yields that the asymptotic dimension of closed
$3$-dimensional Alexandrov spaces is at most three. Thus, we obtain that the Novikov conjecture holds for closed
$4$-manifolds with such a geometric decomposition and for closed
$3$-dimensional Alexandrov spaces. Consequences of these results include a vanishing result for the Yamabe invariant of certain
$0$-surgered geometric
$4$-manifolds and the existence of zero in the spectrum of aspherical smooth
$4$-manifolds with a geometric decomposition.
Communicated by Graeme Wilkin
HCP was supported by UNAM Posdoctoral Program (POSDOC). PSS thanks the Max-Planck-Institute for Mathematics in Bonn.