Jörg Sixt | Searcharxiv

arXiv2008

Stably diffeomorphic manifolds and l_{2q+1}(Z[π])

The monoids l_{2q+1}(Z[π]) detect s-cobordisms amongst certain bordisms between stably diffeomorphic 2q-dimensional manifolds and generalise the Wall simple surgery obstruction groups, L_{2q+1}^s(Z[π]) \subset l_{2q+1}(Z[π]). In this paper we give exact sequences which completely describe l_{2q+1}(Z[π]) as a set and which we use to compute its Grothendieck group. As a consequence we deduce cancellation results for stably diffeomorphic manifolds with polycyclic-by-finite fundamental group.

math.GT↗

arXiv2004

The algebraic theory of Kreck surgery

In the 1980s Matthias Kreck developed a modified surgery theory with obstructions in a hardly understood monoid $l_n(Z[π])$. This paper presents a couple of purely algebraic tools to find out whether an element in $l_{2q}(R)$ is "elementary" i.e. whether a Kreck surgery problem leads to an $h$-cobordism or not.

math.AT↗