http://hdl.handle.net/123456789/26 2026-04-15T21:43:55Z http://hdl.handle.net/123456789/36 Metrizable ball structures Protasov, I.V. A ball structure is a triple (X, P,B), where X, P are nonempty sets and, for any x ∈ X, α ∈ P, B(x, α) is a subset of X, x ∈ B(x, α), which is called a ball of radius α around x. We characterize up to isomorphism the ball structures related to the metric spaces of different types and groups. 2002-09-24T00:00:00Z http://hdl.handle.net/123456789/35 Virtual endomorphisms of groups Nekrashevych, Volodymyr 2002-10-21T00:00:00Z http://hdl.handle.net/123456789/34 On the finite state automorphism group of a rooted tree Lavrenyuk, Yaroslav The normalizer of the finite state automorphism group of a rooted homogeneous tree in the full automorphism group of this tree was investigated. General form of elements in the nor- malizer was obtained and countability of the normalizer was proved. 2002-09-23T00:00:00Z http://hdl.handle.net/123456789/33 Radical theory in BCH-algebras Dudek, W. A.; Jun, Y. B. 2002-05-10T00:00:00Z