Logic Seminar

Hossein Lamei RamandiUniversity of Toronto
Galvin's Question on non-$\sigma$-well ordered linear orders

Friday, October 2, 2020 - 3:00pm
Zoom meeting 931 1107 7941

Assume $\mathcal{C}$ is the class of all linear orders $L$ such that $L$ is not a countable union of well ordered sets, and every uncountable subset of $L$ contains a copy of $\omega_1$. We show it is consistent that $\mathcal{C}$ has minimal elements. This answers an old question due to Galvin.