Date and time: Monday, October 13 at 2PM
Room: 266A.
Speaker: Alberto Levi, University of Sao Paulo.
Abstract: "We present some reflection results for the Lindelöf degree of a topological space X, that is the minimum cardinal k such that every open cover of X has a subcover of cardinality k. After a short review of some facts about exponentiation of singular cardinals, we apply some results of PCF Theory to the problem of reflection. Then, we examine some hypotheses of PCF Theory, like SSH (Shelah's Strong Hypothesis) and SWH (Shelah's Weak Hypothesis), their status in ZFC, and some consequences. Finally, we present some open questions relative to this matter."
Room: 266A.
Speaker: Alberto Levi, University of Sao Paulo.
Abstract: "We present some reflection results for the Lindelöf degree of a topological space X, that is the minimum cardinal k such that every open cover of X has a subcover of cardinality k. After a short review of some facts about exponentiation of singular cardinals, we apply some results of PCF Theory to the problem of reflection. Then, we examine some hypotheses of PCF Theory, like SSH (Shelah's Strong Hypothesis) and SWH (Shelah's Weak Hypothesis), their status in ZFC, and some consequences. Finally, we present some open questions relative to this matter."