# Noon lecture

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On 5.3.2020 at 12:30 in S6, there is the following noon lecture:

# P-ultrafilters on natural numbers

## David Chodounský

## Abstract

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.

list of noon lectures ( 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | newer lectures)

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