TY - JOUR
T1 - More minimal non-σ-scattered linear orders
AU - Shalev, Roy
N1 - Publisher Copyright:
© The Author(s) 2024.
PY - 2024/12
Y1 - 2024/12
N2 - In a recent paper, Cummings, Eisworth and Moore gave a novel construction of minimal non-σ-scattered linear orders of arbitrarily large successor size. It remained open whether it is possible to construct these orders at other cardinals. Here, it is proved that in Gödel’s constructible universe, these orders exist at any regular uncountable cardinal κ that is not weakly compact. In fact, for any cardinal κ as above we obtain 2κ many such orders which are pairwise non-embeddable. At the level of ℵ1, their work answered an old question of Baumgartner by constructing from ♢ a minimal Aronszajn line that is not Souslin. Our uniform construction is based on the Brodsky–Rinot proxy principle which at the level of ℵ1 is strictly weaker than ♢.
AB - In a recent paper, Cummings, Eisworth and Moore gave a novel construction of minimal non-σ-scattered linear orders of arbitrarily large successor size. It remained open whether it is possible to construct these orders at other cardinals. Here, it is proved that in Gödel’s constructible universe, these orders exist at any regular uncountable cardinal κ that is not weakly compact. In fact, for any cardinal κ as above we obtain 2κ many such orders which are pairwise non-embeddable. At the level of ℵ1, their work answered an old question of Baumgartner by constructing from ♢ a minimal Aronszajn line that is not Souslin. Our uniform construction is based on the Brodsky–Rinot proxy principle which at the level of ℵ1 is strictly weaker than ♢.
KW - Aronszajn
KW - Constructible universe
KW - Countryman line
KW - Forcing
KW - Linear order
KW - Scattered
UR - http://www.scopus.com/inward/record.url?scp=85211343377&partnerID=8YFLogxK
U2 - 10.1007/s40879-024-00780-y
DO - 10.1007/s40879-024-00780-y
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C2 - 39634172
AN - SCOPUS:85211343377
SN - 2199-675X
VL - 10
JO - European Journal of Mathematics
JF - European Journal of Mathematics
IS - 4
M1 - 74
ER -