94 research outputs found

    Small loop spaces and covering theory of non-homotopically Hausdorff spaces

    Get PDF
    In this paper we devote to spaces that are not homotopically hausdorff and study their covering spaces. We introduce the notion of small covering and prove that every small covering of XX is the universal covering in categorical sense. Also, we introduce the notion of semi-locally small loop space which is the necessary and sufficient condition for existence of universal cover for non-homotopically hausdorff spaces, equivalently existence of small covering spaces. Also, we prove that for semi-locally small loop spaces, XX is a small loop space if and only if every cover of XX is trivial if and only if Ο€1top(X)\pi_1^{top}(X) is an indiscrete topological group.Comment: 7 page

    Spanier spaces and covering theory of non-homotopically path Hausdorff spaces

    Full text link
    H. Fischer et al. (Topology and its Application, 158 (2011) 397-408.) introduced the Spanier group of a based space (X,x)(X,x) which is denoted by \psp. By a Spanier space we mean a space XX such that \psp=\pi_1(X,x), for every x∈Xx\in X. In this paper, first we give an example of Spanier spaces. Then we study the influence of the Spanier group on covering theory and introduce Spanier coverings which are universal coverings in the categorical sense. Second, we give a necessary and sufficient condition for the existence of Spanier coverings for non-homotopically path Hausdorff spaces. Finally, we study the topological properties of Spanier groups and find out a criteria for the Hausdorffness of topological fundamental groups.Comment: 14 pages, 2 figures. arXiv admin note: text overlap with arXiv:1102.0993 by other author

    On locally 1-connectedness of quotient spaces and its applications to fundamental groups

    Full text link
    Let XX be a locally 1-connected metric space and A1,A2,...,AnA_1,A_2,...,A_n be connected, locally path connected and compact pairwise disjoint subspaces of XX. In this paper, we show that the quotient space X/(A1,A2,...,An)X/(A_1,A_2,...,A_n) obtained from XX by collapsing each of the sets AiA_i's to a point, is also locally 1-connected. Moreover, we prove that the induced continuous homomorphism of quasitopological fundamental groups is surjective. Finally, we give some applications to find out some properties of the fundamental group of the quotient space X/(A1,A2,...,An)X/(A_1,A_2,...,A_n).Comment: 11 page
    • …
    corecore