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We consider the realisation problem for normal 1-types of 4-manifolds with a given boundary. More precisely, given a normal 1-type and closed 3-dimensional -manifold , does there exist a compact 4-dimensional -manifold with boundary ? We describe a three stage obstruction theory for the existence of such a 4-manifold, with our main contribution being a `tertiary’ obstruction that we describe geometrically via Wall’s quadratic self-intersection form.

生成讲解博客的中文版本

生成AI智能校验的中文版本