On 05.03.2020 at 12:30 in S6, there is the following noon lecture:
P-ultrafilters on natural numbers
The notion of a P-ultrafilter was introduced by Walter Rudin in 50's and these objects turned out to be of importance in areas such as topology, set theory and combinatorics. A breakthrough result of Saharon Shelah from 1977 states that the existence of P-ultrafilters is not provable using the axioms of ZFC alone.
The talk will review basic fact about P-ultrafilters and introduce new results concerning their non-existence in certain models of ZFC.
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