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申国桢 博士:A choice-free cardinal equality (II)

本站小编 Free考研/2020-05-19



Academy of Mathematics and Systems Science, CAS
Colloquia & Seminars

Speaker: 申国桢 博士,中科院数学院
Inviter:
Title:
A choice-free cardinal equality (II)
Time & Venue:
2019.12.09 09:00-11:00 N602
Abstract:
Fora cardinal $\mathfrak{a}$, let $\mathrm{fin}(\mathfrak{a})$ be the cardinality of the set of all finite subsets of a set which is of cardinality $\mathfrak{a}$. It is proved without the aid of the axiom of choice that for all infinite cardinals $\mathfrak{a}$ and all natural numbers $n$, $2^{(\mathrm{fin}(\mathfrak{a}))^n}=2^{[\mathrm{fin}(\mathfrak{a})]^n}$.On the other hand, it may consistently happen that there exists an infinite cardianl $\mathfrak{a}$ such that $2^{\mathrm{fin}(\mathfrak{a})}<2^{(\mathrm{fin}(\mathfrak{a}))^2}<2^{(\mathrm{fin}(\mathfrak{a}))^3}<\dots<2^{\mathrm{fin}(\mathrm{fin}(\mathfrak{a}))}$.

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