7,832 reputation
21154
bio website tetori.blog.me
location South Korea
age 18
visits member for 1 year, 6 months
seen 4 hours ago

I'm not good at English.

Pushup is too hard :(


12h
comment Does Vitali set imply the axiom of choice
@StrangerLoop As I know, Vitali set and a nonmeasurable set is somewhat different concept - Vitali set is nonmeasurable, but every nonmeasurable set is not Vitali set. Vitali set is a set constructed by specific way.
13h
comment Can one talk about equivalences classes in a class(which might not be a set).
As I see, Scott's trick is helpful your attempt.
Jul
6
comment How is the law of excluded middle necessary for proofs by contradiction?
Which logical system you used for? I think you should provide the logical system which you use. (That is, you should provide the logical axioms and rule of inferences of which you use.)
Jul
2
awarded  Curious
Jul
1
comment increasing sequence in $\omega_1$
@12345 Yes. $\{\min(\omega_1\setminus I_\alpha)\}$ is open singleton set. However, $\min(\omega_1\setminus I_\alpha)$ is always successor ordinal, and the limit of (strictly) increasing ordinal sequence is limit ordinal.
Jul
1
answered increasing sequence in $\omega_1$
Jul
1
revised increasing sequence in $\omega_1$
Add TeX
Jun
29
accepted Model of complete extension of Zermelo set theory
Jun
29
asked Model of complete extension of Zermelo set theory
Jun
29
revised Cardinality of all $\mathbf{\Sigma}^0_\alpha$-sets over Baire space without full choice
deleted 1 character in body
Jun
25
accepted A model which has only one undefinable element over a language with only a finite number of symbols
Jun
25
comment A model which has only one undefinable element over a language with only a finite number of symbols
In third edition of CK, this problem is only one-starred problem. Anyway, I misunderstand the difficulty of this problem before you explain.
Jun
24
asked A model which has only one undefinable element over a language with only a finite number of symbols
Jun
23
reviewed Looks OK Showing that $\lnot Q \lor (\lnot Q \land R) = \lnot Q$ without a truth table
Jun
23
reviewed Close logic\math question
Jun
23
reviewed Close A dense set on $[0,1)$
Jun
20
comment Recursive Set and Complement Problem
$\phi$ means the empty set?
Jun
20
comment Recursive Set Challenge
@frogeyedpeas Fixing a universe of discourse is not a main problem. In this problem, the universe of discourse is the set of natural numbers. (The notion of computability is defined over natural numbers.)
Jun
17
reviewed Close I would like some help please in utilising the normal distribution.
Jun
17
reviewed Close How was the formula for variance of the geometric solution found?