Almost compact fuzzy topological spaces
Almost disjoint families and “never” cardinal invariants
We define two cardinal invariants of the continuum which arise naturally from combinatorially and topologically appealing properties of almost disjoint families of sets of the natural numbers. These are the never soft and never countably paracompact numbers. We show that these cardinals must both be equal to under the effective weak diamond principle , answering questions of da Silva S.G., On the presence of countable paracompactness, normality and property in spaces from almost disjoint families,...
Almost disjoint families and property (a)
We consider the question: when does a Ψ-space satisfy property (a)? We show that if then the Ψ-space Ψ(A) satisfies property (a), but in some Cohen models the negation of CH holds and every uncountable Ψ-space fails to satisfy property (a). We also show that in a model of Fleissner and Miller there exists a Ψ-space of cardinality which has property (a). We extend a theorem of Matveev relating the existence of certain closed discrete subsets with the failure of property (a).
Alternative definitions of -density topology
Amoeba relation and Galois-Tukey connections
An algebraic and logical approach to continuous images
An application of inaccessible alephs
An Ascoli theorem for sequential spaces.
An Example of a Q-minimal Precompact Topological Group Containing a Nonminimal Closed Normal Subgroup.
An exchange theorem for infinite sums and limits in Banach spaces.
An extension theorem for sober spaces and the Goldman topology.
An independency result in connectification theory
A space is called connectifiable if it can be densely embedded in a connected Hausdorff space. Let be the following statement: “a perfect -space with no more than clopen subsets is connectifiable if and only if no proper nonempty clopen subset of is feebly compact". In this note we show that neither nor is provable in ZFC.
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 observation for simple expansions.
An up-spectral space need not be -spectral.
Another Generalization of Arhangel'skii's Theorem
MSC 2010: 54A25, 54A35.
Aposyndesis in
We consider the Golomb and the Kirch topologies in the set of natural numbers. Among other results, we show that while with the Kirch topology every arithmetic progression is aposyndetic, in the Golomb topology only for those arithmetic progressions with the property that every prime number that divides also divides , it follows that being connected, being Brown, being totally Brown, and being aposyndetic are all equivalent. This characterizes the arithmetic progressions which are aposyndetic...
Application of covering sets
Application on local discrete expansion.
Applications of maximal μ-open sets in generalized topology and quasi topology
In this paper, some fundamental properties of maximal μ-open sets such as decomposition theorem for a maximal μ-open set, are given in a generalized topological space. Some basic properties of intersection of maximal μ-open sets are established, cohere the law of μ-radical μ-closure in a quasi topological space is obtained, among the other things.