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Published online by Cambridge University Press: 04 February 2021
Fundamental group of a manifold gives a deep effect on its underlying smooth structure. In this paper we introduce a new variant of the Donaldson invariant in Yang–Mills gauge theory from twisting by the Picard group of a 4-manifold in the case when the fundamental group is free abelian. We then generalise it to the general case of fundamental groups by use of the framework of non commutative geometry. We also verify that our invariant distinguishes smooth structures between some homeomorphic 4-manifolds.
Supported by JSPS KAKENHI Grant Number JP17H02841
Supported by JSPS KAKENHI Grant Number JP19K03493
Supported by grants NSFC-11801178 and Shanghai Rising-Star Program 19QA1403200.