bio | website | ims.nju.edu.cn/~yuliang |
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location | China | |
age | ||
visits | member for | 4 years, 4 months |
seen | 1 hour ago | |
stats | profile views | 869 |
A mathematical logician.
May
17 |
comment |
Minimal degrees of structures
You don't need pb-genericity. It is not difficult to see that every ANC degree bounds a 1-generic degree (I think that it was already proved in the same DJS paper.) |
Apr
23 |
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Reference for “if the set $A$ is Suslin, then every $\Sigma^1_1(A)$ set is Suslin”
Have you checked Moschovakis book? or Cabal seminar? |
Apr
17 |
awarded | Fanatic |
Apr
13 |
awarded | Yearling |
Apr
5 |
comment |
Degree of unsolvability of finding a open approximation to a Borel set, given its Borel code
Peter Hinman (Hinman, Peter G. Some applications of forcing to hierarchy problems in arithmetic. Z. Math. Logik Grundlagen Math. 15 1969 341–352. ) investigated something related your question based on Sacks work. |
Apr
4 |
answered | Degree of unsolvability of finding a open approximation to a Borel set, given its Borel code |
Mar
10 |
answered | Borel cross section |
Jan
26 |
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Adding a real with infinite conditions
Jockusch told me that a similar method (restrict the conditions with the recursive ones) was also used by Spector, and later by Lachlan, to construct minimal Turing degrees. |
Nov
6 |
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Are there sets which are computable in one model, but uncomputable in another?
It would make induction fail. |
Nov
6 |
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Are there sets which are computable in one model, but uncomputable in another?
Concerning the last question. Any infinite subset of $(\mathbb{N})^U$ in $U$ does not exist in any proper extension $V$ of $U$. Otherwise, $(\mathbb{N})^U$ belongs to $V$, a contradiction. |
Sep
30 |
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Sets computable from enough hints
@Dan, you are right. Thanks. |
Sep
29 |
revised |
Sets computable from enough hints
edited body |
Sep
29 |
revised |
Sets computable from enough hints
added 6 characters in body |
Sep
29 |
revised |
Sets computable from enough hints
added 120 characters in body |
Sep
29 |
revised |
Sets computable from enough hints
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Sep
29 |
answered | Sets computable from enough hints |
Sep
24 |
awarded | Autobiographer |
Jul
24 |
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The (global) theory of Borel equivalence relations
At least the Louveau-Velickovic's result implies the $\Sigma_1$-theory of $(\mathcal{B},\leq_B)$ is decidable. |
Jul
23 |
answered | Are lightface \Delta-1-1 classes of reals describable with hyperarthmetic formulae? |
Jul
23 |
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Are lightface \Delta-1-1 classes of reals describable with hyperarthmetic formulae?
This is a reformulation of the well known result due to Kleene which says that every $\Delta^1_1$ set of reals has a recursive Borel code. The details can be found either in Moschovakis book or Thm 2.7.2 in my joint book with CT. |