Stable equivalence relations on 4-manifolds
Daniel Kasprowski, John Nicholson, Simona Veselá
TL;DR
The article develops a comprehensive framework for stable equivalence relations among closed oriented smooth 4-manifolds using Kreck's modified surgery, recasting these relations as ξ-bordism classes modulo subgroups of Ω4(ξ). It proves a sharp correspondence between six geometric stable relations and algebraic data in Ω4(ξ), via κ2^h, κ2^s, and the pri/sec/ter invariants arising from the James spectral sequence. A key application shows that closed oriented homotopy equivalent 4-manifolds with abelian fundamental groups are stably diffeomorphic, and it provides algebraic obstructions to the existence of smooth 4-manifolds that are homotopy equivalent but not simple homotopy equivalent up to stabilisation. The paper also determines stable rigidity for several finite groups (abelian, quaternion, dihedral, semi-dihedral, modular maximal-cyclic) and analyzes the interplay between stable and unstable equivalence relations, including cancellation phenomena and their impact on 4-manifold classification across topological and smooth categories.
Abstract
Kreck's modified surgery gives an approach to classifying smooth $2n$-manifolds up to stable diffeomorphism, i.e. up to connected sum with copies of $S^n \times S^n$. In dimension 4, we use a combination of modified and classical surgery to study various stable equivalence relations which we compare to stable diffeomorphism. Most importantly, we consider homotopy equivalence up to stabilisation with copies of $S^2 \times S^2$. As an application, we show that closed oriented homotopy equivalent 4-manifolds with abelian fundamental group are stably diffeomorphic. We give analogues of the cancellation theorems of Hambleton--Kreck for stable homeomorphism for homotopy up to stabilisations. Finally, we give a complete algebraic obstruction to the existence of closed smooth 4-manifolds which are homotopy equivalent but not simple homotopy equivalent up to connected sum with $S^2 \times S^2$.
