This paper studies how one can spread points in the Besicovitch space in order to keep them far one from another. We first study the general case and then what happens if the chosen points are all regular Toeplitz configurations or all quasiperiodic configurations.

For several instances of metric largeness like enlargeability or having hyperspherical universal covers, we construct non-large sub-vectorspaces in the rational homology of finitely generated groups. The functorial properties of this construction imply that the corresponding largeness properties of closed manifolds depend only on the image of their fundamental classes under the classifying map....

In the first part of this paper, we let G be a finitely-generated amenable group such that G/[G,G] is torsion-free. We suppose that G acts by homeomorphisms homotopic to the identity on a manifold M , and give conditions on M which imply that such an action must lift to an action on the universal cover M̃ . The circle, all 2-manifolds except the open annulus, and most compact 3-manifolds satisfy...

Let f : A → B be a covering map. We say A has e filtered ends with respect to f (or B) if for some filtration {Kn} of B by compact subsets, A − f(Kn) “eventually” has e components. The main theorem states that if Y is a (suitable) free H-space, if K < H has infinite index, and if Y has a positive finite number of filtered ends with respect to H\Y , then Y has one filtered end with respect to K\...

In this paper, three types of (philosophical, optimistic and pessimistic) multigranulation single valued neutrosophic (SVN) covering-based rough set models are presented, and these three models are applied to the problem of multi-criteria group decision making (MCGDM).Firstly, a type of SVN covering-based rough set model is proposed.Based on this rough set model, three types of mult...

In this note we continue the study of asymptotic invariants of Riemannian tori (e.g. see [BuI] and references there). By asymptotic invariants we mean invariants which do not change under passing to finite covers. In [BuI] we show that the asymptotic volume growth of a Riemannian torus is at least as fast as that of a flat one. One may ask what are the possible values of “asymptotic isoperimetr...

A graph group, or right-angled Artin group, is a group given by a presentation where the only relators are commutators of the generators. A graph group presentation corresponds in a natural way to a simplicial graph, with each generator corresponding to a vertex, and each commutator relator corresponding to an edge. Suppose that G is a graph group whose corresponding graph is a tree and H is a ...

Suppose S is a surface of genus ≥ 2, f : S → S is a surface homeomorphism isotopic to a pseudo-Anosov map α and suppose S̃ is the universal cover of S and F and A are lifts of f and α respectively. A result of A. Fathi shows there is a semiconjugacy Θ : S̃ → L̄ × L̄ from F to Ā, where L̄ (L̄) is the completion of the R-tree of leaves of the stable (resp. unstable) foliation for A and Ā is the map ind...

We consider the following question: given A ∈ SL(2,R), which potentials q for the second order Sturm-Liouville problem have A as its Floquet multiplier? More precisely, define the monodromy map μ taking a potential q ∈ L2([0, 2π]) to μ(q) = Φ̃(2π), the lift to the universal cover G = ̃ SL(2,R) of SL(2,R) of the fundamental matrix map Φ : [0, 2π] → SL(2,R), Φ(0) = I, Φ(t) = (