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21h
comment Prove that the Cardinality of $| \Bbb R \times \Bbb Z |$ has the same cardinality of $\Bbb R$
@youngpadawan That is same as I mentioned.
23h
revised Prove that the Cardinality of $| \Bbb R \times \Bbb Z |$ has the same cardinality of $\Bbb R$
edited title
23h
comment Prove that the Cardinality of $| \Bbb R \times \Bbb Z |$ has the same cardinality of $\Bbb R$
Have you heard the Cantor-Bernstein theorem?
1d
revised Definition for the set of Real Numbers
edited tags
Jul
27
awarded  Nice Question
Jul
4
accepted $\operatorname{Fn}(\lambda,2,\lambda)$ collapses $\lambda^+$ to $\operatorname{cf}\lambda$ if $\lambda$ is singular?
Jul
4
comment $\operatorname{Fn}(\lambda,2,\lambda)$ collapses $\lambda^+$ to $\operatorname{cf}\lambda$ if $\lambda$ is singular?
@Asaf I intend $\kappa$-c.c. as the nonexistence of an antichain of size $\ge\kappa$. Can I conclude that the problem in the book is wrong?
Jul
4
comment $\operatorname{Fn}(\lambda,2,\lambda)$ collapses $\lambda^+$ to $\operatorname{cf}\lambda$ if $\lambda$ is singular?
@Asaf This forcing satisfies $(2^{<\lambda})^+$-chain condition. Under GCH in $V$, it satisfies $\lambda^+$-c.c. But I could not get how to use this property.
Jul
4
revised $\operatorname{Fn}(\lambda,2,\lambda)$ collapses $\lambda^+$ to $\operatorname{cf}\lambda$ if $\lambda$ is singular?
edited body
Jul
4
revised $\operatorname{Fn}(\lambda,2,\lambda)$ collapses $\lambda^+$ to $\operatorname{cf}\lambda$ if $\lambda$ is singular?
added 8 characters in body
Jul
4
revised $\operatorname{Fn}(\lambda,2,\lambda)$ collapses $\lambda^+$ to $\operatorname{cf}\lambda$ if $\lambda$ is singular?
added 9 characters in body
Jul
4
asked $\operatorname{Fn}(\lambda,2,\lambda)$ collapses $\lambda^+$ to $\operatorname{cf}\lambda$ if $\lambda$ is singular?
Jul
3
revised Proving that $\sf Add$$(\aleph_\omega , 1)$ collapses cardinals $\leq \aleph_\omega$
Modify some formulas
Jun
15
awarded  Announcer
Jun
13
comment Calculating the limit $\lim((n!)^{1/n})$
@AbdouAbdou The part you mentioned is an inequality, not an equality. (see the $\ge$ symbol.)
Jun
13
revised Calculating the limit $\lim((n!)^{1/n})$
deleted 3 characters in body
Jun
7
revised Summation closed form for $k^{n^p}$
edited title
Jun
7
comment What is $\operatorname{Gal}(\mathbb{Q (2^{1/3})}/\mathbb{Q})$?
Your proof seems fine.
Jun
5
comment Ordinal exponentiation, is $3^\mu = \mu$?
In general, $2^\mu = \mu$ implies $3^\mu = \mu$.
Jun
2
comment What do the ZFC axioms look like in terms of subset?
I saw an Q&A from MO that $\in$ is not definable from $\subseteq$ before. Hamkins answers it, as far as I remember, but I can't find it.