Parallelizability of 4-dimensional Infrasolvmanifolds
نویسنده
چکیده
We show that if M is an orientable 4-dimensional infrasolvmanifold and either β = β1(M ;Q) ≥ 2 or M is a Sol 0or a Sol m,n -manifold (with m 6= n) then M is parallelizable. There are non-parallelizable examples with β = 1 for each of the other solvable Lie geometries E, Nil, Sol 1, Nil 3×E1 and Sol3×E1. We also determine which non-orientable flat 4-manifolds have a Pinor Pin-structure, and consider briefly this question for the other
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