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I'm a graduate student at UC Berkeley, studying mathematical logic. I'm especially interested in reverse mathematics and abstract model theory.

2d
comment Non Satisfiability of disjuction
This is probably a homework problem, and definitely not appropriate for MO; mathstackexchange would be a better fit.
Apr
14
comment Universal anti-Horn classes?
I suspect that's supposed to allow $\alpha_i$ to be $T$, not just $\alpha_0$?
Apr
9
comment Elementary book on Matrices
This is a good question, but not for this site; mathstackexchange would be a better fit.
Apr
5
comment Some Non-Trivial Algebraic(Rational) Number
I think you'll be interested in mathoverflow.net/questions/32967/…. In particular, I think Legendre's constant (en.wikipedia.org/wiki/Legendre%27s_constant, mentioned in the first answer) is a pretty good example.
Apr
5
revised Application of Fraïssé construction in set theory
added 16 characters in body
Apr
5
comment Application of Fraïssé construction in set theory
Sorry, I didn't realize that - fixed.
Apr
2
comment Does PA+Con(PA) entail the existence of non-standard models of PA?
Isn't that the usual statement of Tennenbaum's theorem?
Mar
23
awarded  Enlightened
Mar
23
awarded  Nice Answer
Mar
23
revised Does PA+Con(PA) entail the existence of non-standard models of PA?
added 188 characters in body
Mar
23
comment Does PA+Con(PA) entail the existence of non-standard models of PA?
For what it's worth, I disagree with the vote to close.
Mar
23
answered Does PA+Con(PA) entail the existence of non-standard models of PA?
Mar
18
comment Surjectivity from union of a set system to the set system
I don't think this works - as I wrote in my comment, I don't think there's an injection $f$ from $\bigcup\mathcal{A}$ to $\mathcal{A}$ satisfying $a\in f(a)$, since 0 and 1 must both be sent to the same place.
Mar
18
comment Surjectivity from union of a set system to the set system
If you mean $\{\{0, 1\}\}\cup . . .$, I don't think this works - what is the $f$? Otherwise - if we treat numbers as ordinals - 0 can't be in $\mathcal{A}$ since $\mathcal{A}$ should consist of nonempty sets only.
Mar
18
answered Surjectivity from union of a set system to the set system
Mar
17
awarded  Taxonomist
Mar
15
comment Surjective (strong) reducibility of Borel equivalence relations
If a Borel equivalence relation $E$ has only countably many equivalence classes, isn't each class Borel?
Mar
15
awarded  Nice Answer
Mar
15
revised Independence of the countable axiom of choice
added 58 characters in body
Mar
15
comment Independence of the countable axiom of choice
Yes, exactly: without the axiom of choice, it is possible that a countable union of countable sets - in fact, a countable union of finite sets - might not be countable!