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.

This paper introduces the concept of lacunary p-distance convergence for sequences of complex uncertain variables. This generalization allows the study of convergence over irregular index sets under uncertainty, extending existing convergence frameworks in uncertainty theory. Various properties, algebraic operations, and geometric aspects of the related function space are discussed.