An atriodic tree-like continuum with positive span
An atriodic tree-like continuum with positive span which admits a monotone mapping to a chainable continuum
An embedding theorem for semigroups of continuous selfmaps.
An Exactly Two-to-One Map from an Indecomposable Chainable Continuum
It is shown that a certain indecomposable chainable continuum is the domain of an exactly two-to-one continuous map. This answers a question of Jo W. Heath.
An example concerning the Whitehead Theorem in shape theory
An example for mappings related to confluence
Confluence of a mapping between topological spaces can be defined by several ways. J.J. Charatonik asked if two definitions of the confluence using the components and quasi-components are equivalent for surjective mappings with compact point inverses. We give the negative answer to this question in Example 2.1.
An example for mappings related to semi-confluence.
An example of 2-dimensional quasihomeomorphic sets
An example of a monostratiform λ-dendroid
An example of a non-compact locally compact arcwise connected metric space with the fixed point property
An example of strongly self-homeomorphic dendrite not pointwise self-homeomorphic
Such spaces in which a homeomorphic image of the whole space can be found in every open set are called self-homeomorphic. W.J. Charatonik and A. Dilks asked if any strongly self-homeomorphic dendrite is pointwise self-homeomorphic. We give a negative answer in Example 2.1.
An example related to strongly pointwise self-homeomorphic dendrites
Such spaces in which a homeomorphic image of the whole space can be found in every open set are called self-homeomorphic. W.J. Charatonik and A. Dilks posed a problem related to strongly pointwise self-homeomorphic dendrites. We solve this problem negatively in Example 2.1.
An extension theorem for sober spaces and the Goldman topology.
An infinitary version of Sperner's Lemma
We prove an extension of the well-known combinatorial-topological lemma of E. Sperner to the case of infinite-dimensional cubes. It is obtained as a corollary to an infinitary extension of the Lebesgue Covering Dimension Theorem.
An interesting plane dendroid
An invariant of bi-Lipschitz maps
A new numerical invariant for the category of compact metric spaces and Lipschitz maps is introduced. This invariant takes a value less than or equal to 1 for compact metric spaces that are Lipschitz isomorphic to ultrametric ones. Furthermore, a theorem is provided which makes it possible to compute this invariant for a large class of spaces. In particular, by utilizing this invariant, it is shown that neither a fat Cantor set nor the set is Lipschitz isomorphic to an ultrametric space.
An irrational problem
Given a topological space ⟨X,⟩ ∈ M, an elementary submodel of set theory, we define to be X ∩ M with topology generated by . Suppose is homeomorphic to the irrationals; must ? We have partial results. We also answer a question of Gruenhage by showing that if is homeomorphic to the “Long Cantor Set”, then .
An n-dimensional compactum which remains n-dimensional after removing all Cantor n-manifolds
An n-dimensional version of Wage's example
An uncountable collection of mutually exclusive planar atriodic tree-like continua with positive span