3,100 reputation
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bio website dorais.org
location Hanover, NH
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visits member for 4 years, 5 months
seen 15 hours ago

I like math and a few other things...


Dec
9
awarded  Precognitive
Oct
2
answered Existence of a perfect measurable set
Oct
2
awarded  Commentator
Oct
2
comment Existence of a perfect measurable set
It depends how you define Lebesgue measure, but many definitions make inner regularity obvious.
Oct
2
comment Existence of a perfect measurable set
The intermediate value argument is strange... How is the domain of $m^*$ a connected topological space?
Sep
28
comment ZF is almost finitely axiomatizable
Yes, the word "proper" (which was missing earlier) is crucial otherwise you might run out of ordinals...
Sep
28
comment ZF is almost finitely axiomatizable
Can you formulate the exercise exactly as stated by Kunen? The way I read your formulation, there is no such finite list of axioms.
Sep
28
answered Real-measurable cardinals that are not measurable ones
Sep
27
revised Cardinality of $H(\kappa)$
added 3 characters in body
Sep
27
comment Cardinality of $H(\kappa)$
@Martin: I just expanded the hint for part 2.
Sep
27
revised Cardinality of $H(\kappa)$
addendum
Sep
27
answered Cardinality of $H(\kappa)$
Sep
20
comment Countability of disjoint intervals
This is a typo. The statement should read: "every collection of disjoint open intervals in R is countable."
Sep
16
comment Uncountable ordinals without power set axiom
Yes, Asaf. If $\kappa > \omega$ is regular then $H(\kappa)$, the family of sets whose transitive closure has size less than $\kappa$, is a model of ZFC-P in which all sets have size at most $\kappa$. (Regularity is needed for the replacement axiom to hold.)
Sep
16
answered Uncountable ordinals without power set axiom
Aug
23
answered Choice function on $\mathcal P (\mathbb R) \setminus \{ \emptyset\}$
Aug
18
awarded  Nice Answer
Jul
30
comment Perfect set without rationals
Hi Joel! Nice answer!
Jul
30
revised Why is compactness in logic called compactness?
addendum
Jul
28
answered Perfect set without rationals