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Feb
4
awarded  Organizer
Feb
4
revised How to prove that $k^3+3k^2+2k$ is always divisible by $3$?
Replaced the discrete-math tag
Feb
4
suggested approved edit on How to prove that $k^3+3k^2+2k$ is always divisible by $3$?
Feb
2
accepted Direct constuction of nonlow noncomplete c.e. sets
Feb
1
revised Direct constuction of nonlow noncomplete c.e. sets
edited title
Feb
1
asked Direct constuction of nonlow noncomplete c.e. sets
Jan
26
answered Does a finite first-order theory which has a model always have a finite model?
Dec
11
accepted Comparing different relativizations in computability
Dec
3
awarded  Yearling
Nov
16
comment Primitive recursion and $\Delta^0_0$
1. I knew this, as stated above. 2. By a similar argument to yours, one could even show that $\Delta^0_0$ cannot be "syntactically characterized". Obviously this is not what I mean by this phrase.
Nov
6
awarded  Cleanup
Nov
6
revised What are non-monotonous computable convergent sequences of rationals with non-computable rate of convergence?
rolled back to a previous revision
Nov
3
comment On Fraenkel-Mostowski choiceless set theory
For 2. which part of Jech are you talking about?
Nov
1
revised On Fraenkel-Mostowski choiceless set theory
added 2 characters in body
Nov
1
comment On Fraenkel-Mostowski choiceless set theory
For 2 - Kunen wants us to assume ZF - foundation and work in that theory.
Nov
1
revised On Fraenkel-Mostowski choiceless set theory
added 26 characters in body
Oct
31
asked On Fraenkel-Mostowski choiceless set theory
Oct
26
comment Incomparable hyperdegrees in $\Delta^1_2$, where one of the two is given
@喻良 Is it possible for you to cite a textbook?
Oct
26
comment $\Pi^1_1$ singletons and $\Delta^1_2$ wellorders on $\omega$ in $L$
can you further say $\omega_1^x$ has a $\Pi^1_1(x)$ for any real $x$? I remember seeing this in a book.
Oct
26
accepted $\Pi^1_1$ singletons and $\Delta^1_2$ wellorders on $\omega$ in $L$