On the Extended Kerr-Newman-Bertotti-Robinson Spacetime: Two Black Holes and a Naked Singularity in Bertotti-Robinson Universe

We introduce new coordinates that extend the Kerr–Newman–Bertotti–Robinson spacetime consistently with the previous reciprocal continuation. In these coordinates, the two points at $\mathrm{\Omega }=0$ are resolved into complete Bertotti–Robinson null infinities. The extended spacetime describes two black holes sharing a common exterior of nontrivial topology, together with a naked ring singularity. In the regular static limit, the new coordinates globally identify the spacetime with the balanced Alekseev–García geometry.