4 papers · 1 filter
Four-manifolds, two-complexes and the quadratic bias invariant
Ian Hambleton, John Nicholson
Kreck and Schafer produced the first examples of stably diffeomorphic closed smooth 4-manifolds which are not homotopy equivalent. They were constructed by applying the doubling co…
Stable equivalence relations on 4-manifolds
Daniel Kasprowski, John Nicholson, Simona Veselá +1
Kreck's modified surgery gives an approach to classifying smooth -manifolds up to stable diffeomorphism, i.e. up to connected sum with copies of . In dimension…
Generalised doubles and simple homotopy types of high dimensional manifolds
Csaba Nagy, John Nicholson, Mark Powell
We characterise the set of fundamental groups for which there exist -manifolds that are -cobordant (hence homotopy equivalent) but not simple homotopy equivalent, when is…
On the universal pairing for 2-complexes
Mikhail Khovanov, Vyacheslav Krushkal, John Nicholson
The universal pairing for manifolds was defined and shown to lack positivity in dimension 4 by Freedman et al. We prove an analogous result for 2-complexes, and also show that the…