82 research outputs found

    Uniformizable functional Alexandroff spaces

    Full text link
    In the following text we show that the Alexandroff space XX is uniformizable if and only if the collection of all smallest neighbourhoods is a partition of XX. Moreover the Alexandroff space XX is uniformizable and functional Alexandroff (kβˆ’k-primal) if and only if the collection of all smallest neighbourhoods is a partition of XX into its finite subsets.Comment: 8 page

    Set-theoretical entropies of weighted generalized shifts

    Full text link
    In this paper for a finite field FF, a nonempty set Ξ“\Gamma, a self--map Ο†:Ξ“β†’Ξ“\varphi:\Gamma\to\Gamma and a weight vector w∈FΞ“\mathfrak{w}\in F^\Gamma, we show that the set--theoretical entropy of the weighted generalized shift σφ,w:FΞ“β†’FΞ“\sigma_{\varphi,\mathfrak{w}}:F^\Gamma\to F^\Gamma is either zero or +∞+\infty, moreover it is equal to zero if and only if σφ,w\sigma_{\varphi,\mathfrak{w}} is quasi--periodic. On the other hand after characterizing all conditions under which σφ,w:FΞ“β†’FΞ“\sigma_{\varphi,\mathfrak{w}}:F^\Gamma\to F^\Gamma is of finite fibre, we show that the cotravariant set--theoretical entropy of the finite fibre σφ,w:FΞ“β†’FΞ“\sigma_{\varphi,\mathfrak{w}}:F^\Gamma\to F^\Gamma depends only on Ο†\varphi and supp(w)\rm{supp}(\mathfrak{w}). In final sections we study the restriction of σφ,w\sigma_{\varphi,\mathfrak{w}} to the direct sum ⨁ΓF\mathop{\bigoplus}\limits_{\Gamma}F
    • …
    corecore