|Responsables :||S. Anscombe, A. Khélif, A. Vignati|
|Email des responsables :||firstname.lastname@example.org, email@example.com|
|Adresse :||Sophie Germain|
|Orateur(s)||Asaf Karaglia - University of East Anglia,|
|Titre||Countable unions of countable sets, their power sets, and the axiom of choice|
|Horaire||15:15 à 16:15|
The union of countably many countable sets is countable, assuming the axiom of choice, and its power set is finite or the same size as the real numbers. But what happens without the axiom of choice? We will go over the basic results and slowly builds towards the theorem of D.B. Morris: There is no bound on how many subsets a countable union of countable sets can have.