Kawauchi proved that every strongly negative amphichiral knot K ⊂ S³ bounds a smoothly embedded disk in some rational homology ball V_K, whose construction a priori depends on K. We show that V_K is independent of K up to diffeomorphism. Thus, a single 4-manifold, along with connected sums thereof, accounts for all known examples of knots that are rationally slice but not slice.

The author was supported by NSF grant DMS-2203860.