32 research outputs found

    On noncontractible compacta with trivial homology and homotopy groups

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    We construct an example of a Peano continuum XX such that: (i) XX is a one-point compactification of a polyhedron; (ii) XX is weakly homotopy equivalent to a point (i.e. πn(X)\pi_n(X) is trivial for all n0n \geq 0); (iii) XX is noncontractible; and (iv) XX is homologically and cohomologically locally connected (i.e. XX is a HLCHLC and clcclc space). We also prove that all classical homology groups (singular, \v{C}ech, and Borel-Moore), all classical cohomology groups (singular and \v{C}ech), and all finite-dimensional Hawaiian groups of XX are trivial

    On nerves of fine coverings of acyclic spaces

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    The main results of this paper are: (1) If a space XX can be embedded as a cellular subspace of Rn\mathbb{R}^n then XX admits arbitrary fine open coverings whose nerves are homeomorphic to the nn-dimensional cube Dn\mathbb{D}^n; (2) Every nn-dimensional cell-like compactum can be embedded into (2n+1)(2n+1)-dimensional Euclidean space as a cellular subset; and (3) There exists a locally compact planar set which is acyclic with respect to \v{C}ech homology and whose fine coverings are all nonacyclic

    On the second homotopy group of SC(Z)SC(Z)

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    In our earlier paper (K. Eda, U. Karimov, and D. Repov\v{s}, \emph{A construction of simply connected noncontractible cell-like two-dimensional Peano continua}, Fund. Math. \textbf{195} (2007), 193--203) we introduced a cone-like space SC(Z)SC(Z). In the present note we establish some new algebraic properties of SC(Z)SC(Z)

    On Snake cones, Alternating cones and related constructions

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    We show that the Snake on a square SC(S1)SC(S^1) is homotopy equivalent to the space AC(S1)AC(S^1) which was investigated in the previous work by Eda, Karimov and Repov\vs. We also introduce related constructions CSC()CSC(-) and CAC()CAC(-) and investigate homotopical differences between these four constructions. Finally, we explicitly describe the second homology group of the Hawaiian tori wedge

    A nonaspherical cell-like 2-dimensional simply connected continuum and related constructions

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    We prove the existence of a 2-dimensional nonaspherical simply connected cell-like Peano continuum (the space itself was constructed in one of our earlier papers). We also indicate some relations between this space and the well-known Griffiths' space from the 1950's

    On the fundamental group of R^3 modulo the Chase-Chaberlin continuum

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    It has been known for a long time that the fundamental group of the quotient of R^3 by the Case-Chamberlin continuum is nontrivial. In the present paper we prove that this group is in fact, uncountable
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