Displaying similar documents to “Vector sets with no repeated differences”

Free spaces

Jian Song, E. Tymchatyn (2000)

Fundamenta Mathematicae

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A space Y is called a free space if for each compactum X the set of maps with hereditarily indecomposable fibers is a dense G δ -subset of C(X,Y), the space of all continuous functions of X to Y. Levin proved that the interval I and the real line ℝ are free. Krasinkiewicz independently proved that each n-dimensional manifold M (n ≥ 1) is free and the product of any space with a free space is free. He also raised a number of questions about the extent of the class of free spaces. In this...

A strongly non-Ramsey uncountable graph

Péter Komjáth (1997)

Fundamenta Mathematicae

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It is consistent that there exists a graph X of cardinality ℵ 1 such that every graph has an edge coloring with ℵ 1 colors in which the induced copies of X (if there are any) are totally multicolored (get all possible colors).

On a problem of Steve Kalikow

Saharon Shelah (2000)

Fundamenta Mathematicae

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The Kalikow problem for a pair (λ,κ) of cardinal numbers,λ > κ (in particular κ = 2) is whether we can map the family of ω-sequences from λ to the family of ω-sequences from κ in a very continuous manner. Namely, we demand that for η,ν ∈ ω we have: η, ν are almost equal if and only if their images are. We show consistency of the negative answer, e.g., for ℵ ω but we prove it for smaller cardinals. We indicate a close connection with the free subset property and its variants. ...

Σ -products of paracompact Čech-scattered spaces

Hidenori Tanaka (2006)

Commentationes Mathematicae Universitatis Carolinae

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In this paper, we shall discuss Σ -products of paracompact Čech-scattered spaces and show the following: (1) Let Σ be a Σ -product of paracompact Čech-scattered spaces. If Σ has countable tightness, then it is collectionwise normal. (2) If Σ is a Σ -product of first countable, paracompact (subparacompact) Čech-scattered spaces, then it is shrinking (subshrinking).