2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/69747Being inspired by a work of Curtis T. McMullen about a very impressive automorphism of a K3 surface of Picard number zero, we shall clarify the structure of the bimeromorphic automorphism group of a non-projective hyperkähler manifold, up to finite group factor. We also discuss relevant topics, especially, new counterexamples of Kodaira's problem about algebraic approximation of a compact Kähler manifold.26 pages, title is changed, Theorem 1.5 is much generalized (to any non-projective case and bimeromorphic automorphisms)Algebraic Geometry14J50, 14J40, 14J28, 11R06text