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Corrigendum to: “Aspherical four-manifolds and the centres of two-knot groups”
out that the proof of the key Lemma on "hopfian" rings in w of [1] is incorrect.As I have been unable to find a correct argument, the results on pages 465-469 are moot.(Corollaries 2 and 3 on page 470 are true as it is easy to see that the lemma …