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math.GT2000
Cycles, submanifolds, and structures on normal bundles
C. Bohr, B. Hanke, D. Kotschick
We give explicit examples of degree 3 cohomology classes not Poincare dual to submanifolds, and discuss the realisability of homology classes by submanifolds with Spin-C normal bun…
math.GT2000
Immersions of surfaces in almost complex 4-manifolds
Christian Bohr
In this note, we investigate the relation between double points and complex points of immersed surfaces in almost-complex 4-manifolds and show how estimates for the minimal genus o…
math.GT2000
On the signatures of even 4-manifolds
Christian Bohr
In this paper, we prove a number of inequalities between the signature and the Betti numbers of a 4-manifold with even intersection form. Furthermore, we introduce a new geometric…