Uniqueness of the non-singular family and characterisation of cosmological models

Uniqueness of the Trautman--Bondi mass

Uniqueness properties of the Kerr metric

Uniqueness results for ill posed characteristic problems in curved space-times

Uniqueness theorem for 5-dimensional black holes with two axial Killing fields

Uniqueness theorem for BMS-invariant states of scalar QFT on the null boundary of asymptotically flat spacetimes and bulk-boundary observable algebra correspondence

Uniqueness theorems for static black holes in metric-affine gravity

Uniqueness theorems for static spacetimes containing marginally outer trapped surfaces

Unitarity and Causality in Generalized Quantum Mechanics for Non-Chronal Spacetimes

Unitarity and Holography in Gravitational Physics

Unitarity Condition on Quantum Fields in Semiclassical Gravity

Unitarity Restoration in the Presence of Closed Timelike Curves

Unitary and non-unitary evolution in quantum cosmology

Unitary Equivalence of the Metric and Holonomy Formulations of 2+1 Dimensional Quantum Gravity on the Torus

Unitary evolution in Gowdy cosmology

Unitary evolution of free massless fields in de Sitter space-time

Unitary irreducible representations of SL(2,C) in discrete and continuous SU(1,1) bases

Unitary Theory of Evaporating 2D Black Holes

United Approach to the Universe Model and the Local Gravitation Problem

Universal Approach to Cosmological Singularities in Two Dimensional Dilaton Gravity