We consider topological attractors of (possibly infinite) iterated function systems. It is shown that for some class of non-expansive mappings the boundedness of the set of all globally attractive fixed points is equivalent to the boundedness of the attractor. Moreover, such a system fullfils the so-called address theorem.
In this paper we provide a series of examples of nonmaximal orders in a quadratic number field K whose Witt ring does not embed into the Witt ring of K.
10.2478/amsil
English