CAT(0) and CAT(−1) fillings of hyperbolic manifolds

We give new examples of hyperbolic and relatively hyperbolic groups of cohomological dimension d for all $d ≥ 4$ (see Theorem 2.13). These examples result from applying $CAT(0)/CAT(−1)$ filling constructions (based on singular doubly warped products) to finite volume hyperbolic manifolds with toral cusps. The groups obtained have a number of interesting properties, which are established by analyzing their boundaries at infinity by a kind of Morse-theoretic technique, related to but distinct from ordinary and combinatorial Morse theory (see Section 5).