Linear orders and MA + ¬wKH
Zoran Spasojević (1995)
Fundamenta Mathematicae
Similarity:
I prove that the statement that “every linear order of size can be embedded in ” is consistent with MA + ¬ wKH.
Zoran Spasojević (1995)
Fundamenta Mathematicae
Similarity:
I prove that the statement that “every linear order of size can be embedded in ” is consistent with MA + ¬ wKH.
Krzysztof Barański (1998)
Fundamenta Mathematicae
Similarity:
This is the first part of the work studying the family of all rational maps of degree three with two superattracting fixed points. We determine the topological type of the moduli space of and give a detailed study of the subfamily consisting of maps with a critical point which is periodic of period 2. In particular, we describe a parabolic bifurcation in from Newton maps to maps with so-called exotic basins.
Pietro Corvaja, Umberto Zannier (2000)
Acta Arithmetica
Similarity:
Dominique Arlettaz, Nicole Pointet-Tischler (1999)
Fundamenta Mathematicae
Similarity:
It is known that the order of all Postnikov k-invariants of an H-space of finite type is finite. This paper establishes the finiteness of the order of the k-invariants of X in dimensions m ≤ 2n if X is an (n-1)-connected H-space which is not necessarily of finite type (n ≥ 1). Similar results hold more generally for higher k-invariants if X is an iterated loop space. Moreover, we provide in all cases explicit universal upper bounds for the order of the k-invariants of X.
Paul Fabel (1998)
Fundamenta Mathematicae
Similarity:
We prove that the space of orientation preserving homeomorphisms of the 2-sphere which fix pointwise a nontrivial nonseparating continuum is a contractible absolute neighborhood retract homeomorphic to the separable Hilbert space .
Peter Saveliev (1999)
Fundamenta Mathematicae
Similarity:
A Lefschetz-type coincidence theorem for two maps f,g: X → Y from an arbitrary topological space to a manifold is given: , that is, the coincidence index is equal to the Lefschetz number. It follows that if then there is an x ∈ X such that f(x) = g(x). In particular, the theorem contains well-known coincidence results for (i) X,Y manifolds, f boundary-preserving, and (ii) Y Euclidean, f with acyclic fibres. It also implies certain fixed point results for multivalued maps with “point-like”...
Alexander Shibakov (1998)
Fundamenta Mathematicae
Similarity:
For any a countable sequential topological group of sequential order α is constructed using CH.
Davide Ferrario (1998)
Fundamenta Mathematicae
Similarity:
In order to compute the Nielsen number N(f) of a self-map f: X → X, some Reidemeister classes in the fundamental group need to be distinguished. In this paper some algebraic results are given which allow distinguishing Reidemeister classes and hence computing the Reidemeister number of some maps. Examples of computations are presented.
Bjorn Poonen (1998)
Acta Arithmetica
Similarity:
R. Ball, J. Hagler, Yaki Sternfeld (1998)
Fundamenta Mathematicae
Similarity:
Let X be an atom (= hereditarily indecomposable continuum). Define a metric ϱ on X by letting where is the (unique) minimal subcontinuum of X which contains x and y and W is a Whitney map on the set of subcontinua of X with W(X) = 1. We prove that ϱ is an ultrametric and the topology of (X,ϱ) is stronger than the original topology of X. The ϱ-closed balls C(x,r) = y ∈ X:ϱ ( x,y) ≤ r coincide with the subcontinua of X. (C(x,r) is the unique subcontinuum of X which contains x and has...
Marcel Bökstedt, Iver Ottosen (1999)
Fundamenta Mathematicae
Similarity:
Let X be a space with free loop space ΛX and mod two cohomology R = H*X. We construct functors and ℓ(R) together with algebra homomorphisms and . When X is 1-connected and R is a symmetric algebra we show that these are isomorphisms.
Alessandro Andretta, Alberto Marcone (1997)
Fundamenta Mathematicae
Similarity:
We study some natural sets arising in the theory of ordinary differential equations in one variable from the point of view of descriptive set theory and in particular classify them within the Borel hierarchy. We prove that the set of Cauchy problems for ordinary differential equations which have a unique solution is -complete and that the set of Cauchy problems which locally have a unique solution is -complete. We prove that the set of Cauchy problems which have a global solution is...
Ilijas Farah (1999)
Fundamenta Mathematicae
Similarity:
We use Tsirelson’s Banach space ([2]) to define an P-ideal which refutes a conjecture of Mazur and Kechris (see [12, 9, 8]).