Another proof of a result of Jech and Shelah

Péter Komjáth

Czechoslovak Mathematical Journal (2013)

  • Volume: 63, Issue: 3, page 577-582
  • ISSN: 0011-4642

Abstract

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Shelah’s pcf theory describes a certain structure which must exist if ω is strong limit and 2 ω > ω 1 holds. Jech and Shelah proved the surprising result that this structure exists in ZFC. They first give a forcing extension in which the structure exists then argue that by some absoluteness results it must exist anyway. We reformulate the statement to the existence of a certain partially ordered set, and then we show by a straightforward, elementary (i.e., non-metamathematical) argument that such partially ordered sets exist.

How to cite

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Komjáth, Péter. "Another proof of a result of Jech and Shelah." Czechoslovak Mathematical Journal 63.3 (2013): 577-582. <http://eudml.org/doc/260605>.

@article{Komjáth2013,
abstract = {Shelah’s pcf theory describes a certain structure which must exist if $\aleph _\{\omega \}$ is strong limit and $2^\{\aleph _\omega \}>\aleph _\{\omega _1\}$ holds. Jech and Shelah proved the surprising result that this structure exists in ZFC. They first give a forcing extension in which the structure exists then argue that by some absoluteness results it must exist anyway. We reformulate the statement to the existence of a certain partially ordered set, and then we show by a straightforward, elementary (i.e., non-metamathematical) argument that such partially ordered sets exist.},
author = {Komjáth, Péter},
journal = {Czechoslovak Mathematical Journal},
keywords = {partially ordered set; pcf theory; partially ordered set; pcf theory},
language = {eng},
number = {3},
pages = {577-582},
publisher = {Institute of Mathematics, Academy of Sciences of the Czech Republic},
title = {Another proof of a result of Jech and Shelah},
url = {http://eudml.org/doc/260605},
volume = {63},
year = {2013},
}

TY - JOUR
AU - Komjáth, Péter
TI - Another proof of a result of Jech and Shelah
JO - Czechoslovak Mathematical Journal
PY - 2013
PB - Institute of Mathematics, Academy of Sciences of the Czech Republic
VL - 63
IS - 3
SP - 577
EP - 582
AB - Shelah’s pcf theory describes a certain structure which must exist if $\aleph _{\omega }$ is strong limit and $2^{\aleph _\omega }>\aleph _{\omega _1}$ holds. Jech and Shelah proved the surprising result that this structure exists in ZFC. They first give a forcing extension in which the structure exists then argue that by some absoluteness results it must exist anyway. We reformulate the statement to the existence of a certain partially ordered set, and then we show by a straightforward, elementary (i.e., non-metamathematical) argument that such partially ordered sets exist.
LA - eng
KW - partially ordered set; pcf theory; partially ordered set; pcf theory
UR - http://eudml.org/doc/260605
ER -

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