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Spaces with fibered approximation property in dimension n

Taras Banakh, Vesko Valov (2010)

Open Mathematics

A metric space M is said to have the fibered approximation property in dimension n (briefly, M ∈ FAP(n)) if for any ɛ > 0, m ≥ 0 and any map g: 𝕀 m × 𝕀 n → M there exists a map g′: 𝕀 m × 𝕀 n → M such that g′ is ɛ-homotopic to g and dim g′ (z × 𝕀 n) ≤ n for all z ∈ 𝕀 m. The class of spaces having the FAP(n)-property is investigated in this paper. The main theorems are applied to obtain generalizations of some results due to Uspenskij [11] and Tuncali-Valov [10].

Strong Cohomological Dimension

Jerzy Dydak, Akira Koyama (2008)

Bulletin of the Polish Academy of Sciences. Mathematics

We characterize strong cohomological dimension of separable metric spaces in terms of extension of mappings. Using this characterization, we discuss the relation between strong cohomological dimension and (ordinal) cohomological dimension and give examples to clarify their gaps. We also show that I n d G X = d i m G X if X is a separable metric ANR and G is a countable Abelian group. Hence d i m X = d i m X for any separable metric ANR X.

Sur l’invariance de la dimension infinie forte par t-équivalence

Robert Cauty (1999)

Fundamenta Mathematicae

Let X and Y be metric compacta such that there exists a continuous open surjection from C p ( Y ) onto C p ( X ) . We prove that if there exists an integer k such that X k is strongly infinite-dimensional, then there exists an integer p such that Y p is strongly infinite-dimensional.

The dimension of hyperspaces of non-metrizable continua

Wojciech Stadnicki (2012)

Colloquium Mathematicae

We prove that, for any Hausdorff continuum X, if dim X ≥ 2 then the hyperspace C(X) of subcontinua of X is not a C-space; if dim X = 1 and X is hereditarily indecomposable then either dim C(X) = 2 or C(X) is not a C-space. This generalizes some results known for metric continua.

The dimension of X^n where X is a separable metric space

John Kulesza (1996)

Fundamenta Mathematicae

For a separable metric space X, we consider possibilities for the sequence S ( X ) = d n : n where d n = d i m X n . In Section 1, a general method for producing examples is given which can be used to realize many of the possible sequences. For example, there is X n such that S ( X n ) = n , n + 1 , n + 2 , . . . , Y n , for n >1, such that S ( Y n ) = n , n + 1 , n + 2 , n + 2 , n + 2 , . . . , and Z such that S(Z) = 4, 4, 6, 6, 7, 8, 9,.... In Section 2, a subset X of 2 is shown to exist which satisfies 1 = d i m X = d i m X 2 and d i m X 3 = 2 .

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