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Mohammad Golshani
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It is consistent that the answer is no. The following is proved in Beaodouin's thesis ``On uncountable trees and linear orders'', as Theorem 1.10:

Theorem. Assume $\kappa^{<\kappa}=\kappa$ and $\Diamond(E)$ holds, where $E \subseteq \{\alpha < \kappa^+: cf(\alpha)=\kappa \}$.Then there is a normal $\kappa^+$-Aronszajn tree which has no special or Souslin subtree of size $\kappa^+.$

Theorem. Assume $\kappa^{<\kappa}=\kappa$ and $\Diamond(E)$ holds I may mention that the theorem is not stated as above in the paper, where $E \subseteq \{\alpha < \kappa^+: cf(\alpha)=\kappa \}$but looking at the proof, it is clear that the above result is in fact proved.Then there It is a normalalso mentioned in the paper that the case $\kappa^+$-Aronszajn tree which$\kappa=\omega$ has no special or Souslin subtree of size $\kappa^+.$discovered by Hanazawa too.

It is consistent that the answer is no. The following is proved in Beaodouin's thesis ``On uncountable trees and linear orders'', as Theorem 1.10:

Theorem. Assume $\kappa^{<\kappa}=\kappa$ and $\Diamond(E)$ holds, where $E \subseteq \{\alpha < \kappa^+: cf(\alpha)=\kappa \}$.Then there is a normal $\kappa^+$-Aronszajn tree which has no special or Souslin subtree of size $\kappa^+.$

It is consistent that the answer is no. The following is proved in Beaodouin's thesis ``On uncountable trees and linear orders'', as Theorem 1.10:

Theorem. Assume $\kappa^{<\kappa}=\kappa$ and $\Diamond(E)$ holds, where $E \subseteq \{\alpha < \kappa^+: cf(\alpha)=\kappa \}$.Then there is a normal $\kappa^+$-Aronszajn tree which has no special or Souslin subtree of size $\kappa^+.$

I may mention that the theorem is not stated as above in the paper, but looking at the proof, it is clear that the above result is in fact proved. It is also mentioned in the paper that the case $\kappa=\omega$ has discovered by Hanazawa too.

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Mohammad Golshani
  • 32.1k
  • 2
  • 99
  • 198

It is consistent that the answer is no. The following is proved in Beaodouin's thesis ``On uncountable trees and linear orders'', as Theorem 1.10:

Theorem. Assume $\kappa^{<\kappa}=\kappa$ and $\Diamond(E)$ holds, where $E \subseteq \{\alpha < \kappa^+: cf(\alpha)=\kappa \}$.Then there is a normal $\kappa^+$-Aronszajn tree which has no special or Souslin subtree of size $\kappa^+.$