Extensions of nonexpansive mappings in the Hilbert ball with the hyperbolic metric. I.
Tadeusz Kuczumow, Adam Stachura · Czech digital mathematics library · 1988
In an open unit disc AcC we have the Poincare" metric £>,.If T:X->A is a {&,-nonexpansive mapping of a subset X of A into A -, then there exists a p,-nonexpansive mapping T: A->A such that its restriction to X is identical with T.If in a complex Hilbert space H we take an open unit ball B with the hyperbolic metric, then for dim H2T2 the above fact is not true.Similarly as in A n for nZ2. Key words; Hyperbolic metric,