Counting linearly ordered spaces

Gerald Kuba. "Counting linearly ordered spaces." Colloquium Mathematicae 135.1 (2014): 1-14. <http://eudml.org/doc/284343>.

@article{GeraldKuba2014,
abstract = {For a transfinite cardinal κ and i ∈ 0,1,2 let $ℒ_i(κ)$ be the class of all linearly ordered spaces X of size κ such that X is totally disconnected when i = 0, the topology of X is generated by a dense linear ordering of X when i = 1, and X is compact when i = 2. Thus every space in ℒ₁(κ) ∩ ℒ₂(κ) is connected and hence ℒ₁(κ) ∩ ℒ₂(κ) = ∅ if $κ < 2^\{ℵ₀\}$, and ℒ₀(κ) ∩ ℒ₁(κ) ∩ ℒ₂(κ) = ∅ for arbitrary κ. All spaces in ℒ₁(ℵ₀) are homeomorphic, while ℒ₂(ℵ₀) contains precisely ℵ₁ spaces up to homeomorphism. The class ℒ₁(κ) ∩ ℒ₂(κ) contains precisely $2^\{κ\}$ spaces up to homeomorphism for every $κ ≥ 2^\{ℵ₀\}$. Our main results are explicit constructions which prove that both classes ℒ₀(κ) ∩ ℒ₁(κ) and ℒ₀(κ) ∩ ℒ₂(κ) contain precisely $2^\{κ\}$ spaces up to homeomorphism for every κ > ℵ₀. Moreover, for any κ we investigate the variety of second countable spaces in the class ℒ₀(κ) ∩ ℒ₁(κ) and the variety of first countable spaces of arbitrary weight in the class ℒ₂(κ).},
author = {Gerald Kuba},
journal = {Colloquium Mathematicae},
keywords = {linearly ordered spaces; compactness; scattered space},
language = {eng},
number = {1},
pages = {1-14},
title = {Counting linearly ordered spaces},
url = {http://eudml.org/doc/284343},
volume = {135},
year = {2014},
}

TY - JOUR
AU - Gerald Kuba
TI - Counting linearly ordered spaces
JO - Colloquium Mathematicae
PY - 2014
VL - 135
IS - 1
SP - 1
EP - 14
AB - For a transfinite cardinal κ and i ∈ 0,1,2 let $ℒ_i(κ)$ be the class of all linearly ordered spaces X of size κ such that X is totally disconnected when i = 0, the topology of X is generated by a dense linear ordering of X when i = 1, and X is compact when i = 2. Thus every space in ℒ₁(κ) ∩ ℒ₂(κ) is connected and hence ℒ₁(κ) ∩ ℒ₂(κ) = ∅ if $κ < 2^{ℵ₀}$, and ℒ₀(κ) ∩ ℒ₁(κ) ∩ ℒ₂(κ) = ∅ for arbitrary κ. All spaces in ℒ₁(ℵ₀) are homeomorphic, while ℒ₂(ℵ₀) contains precisely ℵ₁ spaces up to homeomorphism. The class ℒ₁(κ) ∩ ℒ₂(κ) contains precisely $2^{κ}$ spaces up to homeomorphism for every $κ ≥ 2^{ℵ₀}$. Our main results are explicit constructions which prove that both classes ℒ₀(κ) ∩ ℒ₁(κ) and ℒ₀(κ) ∩ ℒ₂(κ) contain precisely $2^{κ}$ spaces up to homeomorphism for every κ > ℵ₀. Moreover, for any κ we investigate the variety of second countable spaces in the class ℒ₀(κ) ∩ ℒ₁(κ) and the variety of first countable spaces of arbitrary weight in the class ℒ₂(κ).
LA - eng
KW - linearly ordered spaces; compactness; scattered space
UR - http://eudml.org/doc/284343
ER -