2023/07/08 by Frøyshov, Kim A.
#Differential Geometry (math.DG) #FOS: Mathematics #Geometric Topology (math.GT)
paper · doi:10.48550/arxiv.2307.03950
Using instanton homology with coefficients in Z/2 we construct a homomorphism q2 from the homology cobordism group in dimension 3 to the integers which is not a rational linear combination of the instanton h--invariant and the Heegaard Floer correction term d. If an oriented homology 3--sphere Y bounds a smooth, compact, negative definite 4--manifold without 2--torsion in its homology then q2(Y)≥0, with strict inequality if the intersection form is non-standard.