μ-Separations in generalized topological spaces

This paper takes some investigations on generalized topological spaces with some μ- separations. Some characterizations of μTi-spaces for i = 0,1,2,3,4, μTD-spaces and μR0-spaces are obtained and some relations among these spaces are established.     

On Λ I s -sets and the related notions in ideal topological spaces

In this paper, we define and study the notions of Λ _I ^s -sets, Λ _I ^s -closed sets and I-generalized semi-closed (briefly I-gs-closed) sets by using semi-I-open sets in an ideal topological space. Moreover, we present and characterize two new low separation axioms using the above notions.     

New generalized topologies on generalized topological spaces due to Cs??sz??r

We introduce new types of sets called $\bigwedge_{\mu}$ -sets and $\bigvee_{\mu}$ -sets and study some of their fundamental properties. We then investigate the topologies obtained from these sets.     

On Λ<Subscript>m</Subscript>-sets and related topological spaces

Summary We introduce and investigate three topological spaces <InlineEquation ID=IE"1"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"2"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"3"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"4"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"5"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"6"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"7"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"8"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"9"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"10"><EquationSource Format="TEX"><![CDATA[$]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>(X,\Lambda_m)$, $(X,\Lambda_{mc}^*)$ and $(X,\Lambda_{g\Lambda_m})$ by using $\Lambda_m$-sets, $(\Lambda, m)$-closed sets and generalized $\Lambda_m$-sets, respectively. Especially, we study properties of weak separation axioms on these topological spaces. The investigation enables us to obtain a unified theory of notions related to $\Lambda$-sets [21], semi-$\Lambda$-sets [5] and pre-$\Lambda$-sets [15] in topological spaces.     

A unified theory of contra-(μ,λ)-continuous functions in generalized topological spaces

We introduce a new notion called contra-(μ,λ)-continuous functions as functions on generalized topological spaces?[8]. We obtain some characterizations and several properties of such functions. The functions enable us to formulate a unified theory of several modifications of contra-continuity due to Dontchev?[18].     

Factorization in generalized Calogero–Moser spaces

Using a recent construction of Bezrukavnikov and Etingof, [R. Bezrukavnikov, P. Etingof, Induction and restriction functors for rational Cherednik algebras, arXiv: 0803.3639], we prove that there is a factorization of the Etingof–Ginzburg sheaf on the generalized Calogero–Moser space associated to a complex reflection group. In the case $W=S_n$, this confirms a conjecture of Etingof and Ginzburg, [P. Etingof, V. Ginzburg, Symplectic reflection algebras, Calogero–Moser space, and deformed Harish-Chandra homomorphisms, Invent. Math 147 (2002) 243–348].     

Bernstein's “lethargy” theorem in metrizable topological linear spaces

A version of Bernstein's lethargy theorem is given in a class of vector spaces includingF-spaces and Orlicz-Musielak spaces with condition ₂. This extends results obtained in [9] and [11].     

On Ω-closed sets and Ωs-closed sets in topological spaces

Summary New classes of sets called -closed sets and s-closed sets are introduced and studied. Also, we introduce and study -continuous functions and s-continuous functions and prove pasting lemma for these functions. Moreover, we introduce classes of topological spaces -T_1/2 and -T_s.     

A generalized vector-valued variational principle in Fréchet spaces

In the framework of Frechet spaces, we give a generalized vector-valued Ekeland＇s variational principle, where the perturbation involves the subadditive functions of countable generating semi-norms. By modifying and developing the method of Cammaroto and Chinni, we obtain a density theorem on extremal points of the vector-valued variational principle, which extends and improves the related known results.     

Totally umbilic null hypersurfaces in generalized Robertson–Walker spaces

We show that there is a correspondence between totally umbilic null hypersurfaces in generalized Robertson–Walker spaces and twisted decompositions of the fibre. This allows us to prove that nullcones are the unique totally umbilic null hypersurfaces in the closed Friedmann Cosmological model. We also apply this kind of ideas to static spaces, in particular to Reissner–Nordström and Schwarzschild exterior spacetimes.     

On pα-dual spaces of generalized difference sequence spaces

In this paper, we compute the $p\alpha$-, $p\beta$- and $p\gamma$-duals of the sequence spaces ${?}_{\infty }\left(k^m\right),c\left(k^m\right),c_0\left(k^m\right)$, the $pN$-dual of the sequence spaces ${\Delta }_{v,r}^m\left({?}_{\infty }\right),{\Delta }_{v,r}^m\left(c\right)$ and the $p\alpha$-dual of the sequence spaces ${\Delta }_{v,r}^m\left({?}_{\infty }\right),{\Delta }_{v,r}^m\left(c\right)$ and ${\Delta }_{v,r}^m\left(c_0\right)$.     

The generalized Roper-Suffridge extension operator in Banach spaces (Ⅲ)

Suppose that X is a complex Banach space with the norm ||·|| and n is a positive integer with dim X ≥n≥ 2. In this paper,we consider the generalized Roper-Suffridge extension operator Φn,β2,γ2,...,βn+1,γn+1(f) on the domain Ωp1,p2,...,pn+1 defined by