On the convergence of certain sequences and some applications, II.
On the convergence of implicit Ishikawa iterations with errors to a common fixed point of two mappings in convex metric spaces.
On the convergence of the Ishikawa iterates to a common fixed point of two mappings
Let be a convex subset of a complete convex metric space , and and be two selfmappings on . In this paper it is shown that if the sequence of Ishikawa iterations associated with and converges, then its limit point is the common fixed point of and . This result extends and generalizes the corresponding results of Naimpally and Singh [6], Rhoades [7] and Hicks and Kubicek [3].
On the convergence of the Ishikawa iteration in the class of quasi contractive operators.
On the convergence of -primitives
On the Converse of Caristi's Fixed Point Theorem
Let X be a nonempty set of cardinality at most and T be a selfmap of X. Our main theorem says that if each periodic point of T is a fixed point under T, and T has a fixed point, then there exist a metric d on X and a lower semicontinuous map ϕ :X→ ℝ ₊ such that d(x,Tx) ≤ ϕ(x) - ϕ(Tx) for all x∈ X, and (X,d) is separable. Assuming CH (the Continuum Hypothesis), we deduce that (X,d) is compact.
On the curvature of nonregular saddle surfaces in the hyperbolic and spherical three-space.
On the decomposition of continuous flows on the Polish space
On the deficiency of product spaces
On the definition of a probalistic normed space.
On the density and net weight of regular spaces
We use the cardinal functions ac and lc, due to Fedeli, to establish bounds on the density and net weight of regular spaces which improve some well known bounds. In particular, we use the language of elementary submodels to establish that for every regular space X. This generalizes the following result due to Shapirovskiĭ: for every regular space X.
On the density of the hyperspace of a metric space
We calculate the density of the hyperspace of a metric space, endowed with the Hausdorff or the locally finite topology. To this end, we introduce suitable generalizations of the notions of totally bounded and compact metric space.
On the depth of a continuum
On the descriptive sot theory of the lexicographic square
On the descriptive theory of sets
On the difference property of Borel measurable functions
If an atomlessly measurable cardinal exists, then the class of Lebesgue measurable functions, the class of Borel functions, and the Baire classes of all orders have the difference property. This gives a consistent positive answer to Laczkovich's Problem 2 [Acta Math. Acad. Sci. Hungar. 35 (1980)]. We also give a complete positive answer to Laczkovich's Problem 3 concerning Borel functions with Baire-α differences.
On the differences of upper semicontinuous quasi-continuous functions
On the differentiability of multivalued mappings. II.
On the differentiation theorem in metric groups
On the dimension modulo classes of topological spaces and free topological groups.