Comment: Exact vacuum solution with Hopf structure in general relativity
arXiv:2603.08606
Abstract
Harada's recently announced Kerr-Schild solution of Einstein's equations in general relativity [Phys. Rev. D {\bf 112}, 024020 92025)] is identified as isometric with one of the well-known NUT solutions.
2 pages. Submitted as comment to Phys. Rev. D. Appropriate references to prior work have been added