Many body interactions may modify the topology of physical systems. We have discussed it for a simple 0-D system with non-hermitian hamiltonian. Have a look at our recent paper, “Correlation effects on non-Hermitian point-gap topology in zero dimension: Reduction of topological classification” by Tsuneya Yoshida and Yasuhiro Hatsugai, which has been accepted for publication on 20 July 2021 and published in Phys. Rev. B 104, 075106 – Published 5 August 2021. See also arXiv:2105.12913.