Ultrafilters on singular cardinals of uncountable cofinality
James Cummings, Charles G. Morgan
Abstract
Open-access reader
James Cummings, Charles G. Morgan
Abstract
Open-access reader
We prove that consistently there is a singular cardinal $κ$ of uncountable cofinality such that $2^κ$ is weakly inaccessible, and every regular cardinal strictly between $κ$ and $2^κ$ is the character of some uniform ultrafilter on $κ$.
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We prove that consistently there is a singular cardinal $κ$ of uncountable cofinality such that $2^κ$ is weakly inaccessible, and every regular cardinal strictly between $κ$ and $2^κ$ is the character of some uniform ultrafilter on $κ$.
Key concepts: Cofinality, Uncountable set, Regular cardinal, Kappa, Mathematics, Ultrafilter, Character (mathematics), Discrete mathematics