4 papers
Universal countably chromatic graph
Siiri Kivimäki
We show that the existence of a universal countably chromatic graph of size together with the failure of continuum hypothesis is consistent. The proof is a forcing itera…
Universal wide Aronszajn tree
Siiri Kivimäki
A wide Aronszajn tree is a tree of size with no uncountable branches. Assuming the consistency of the existence of a weakly compact cardinal, we show the consistency of…
Aronszajn trees and maximality
Omer Ben-Neria, Siiri Kivimäki, Menachem Magidor +1
Assuming the consistency of a weakly compact cardinal above a regular uncountable cardinal , we prove the consistency of the existence of a wide -Aronszajn tree, i.e. a tre…
Characterization of
Siiri Kivimaki, Boban Velickovic
The logic was introduced by Shelah in [3]. In [4], he proved that for a strongly compact cardinal , it admits the following algebraic characterization: two stru…