The paper treats a particular type of pseudo-Riemannian spaces, namely quasi-Einstein spaces with gradient defining vector. These spaces are a generalization of well-known Einstein spaces. There are three types of these ...

We introduce a counterpart of the Fr echet distance for the rooted trees in a metric space. Some properties and possible generalizations of this distance are discussed.

We prove that the "sliced" hyperspaces and spaces of probability measures of the rooted R-trees are also rooted R-trees.

Клас K-ультраметричних просторiв є узагальненням класу ультраметричних просторiв. У статтi розглянуто функтори у категорiї (рiвномiрно) K-ультраметричних просторiв та K-нерозтягуючих вiдображень. Зокрема, показано, що ...

The hyperspace of a fuzzy metric space is defined by J. Rodr´ıguez-L´opez and S. Romaguera. In this paper, it is shown that the hyperspace construction determines a functor on the category of fuzzy metric spaces and ...

Weintroduceafuzzyultrametriconthesetofprobabilitymeasureswithcompactsupport defined on a fuzzy metric space. The construction is a counterpart, in the realm of fuzzy ultrametricspaces,oftheconstructionduetoVinkandRutteno ...

We consider functors in the category of non-Archimedean uniform spaces and uniformly continuous maps generated by some normal functors in the category of compact Hausdor spaces. We also show that any natural transformation ...