A measure-theoretic proof of Turing incomparability

نویسنده

  • Chris J. Conidis
چکیده

We prove that if S is an ω-model of weak weak König’s lemma and A ∈ S, A ⊆ ω, is incomputable, then there exists B ∈ S, B ⊆ ω, such that A and B are Turing incomparable. This extends a recent result of Kučera and Slaman who proved that if S0 is a Scott set (i.e. an ω-model of weak König’s lemma) and A ∈ S0, A ⊆ ω, is incomputable, then there exists B ∈ S0, B ⊆ ω, such that A and B are Turing incomparable. 1. Genericity, Randomness, Logic, and Computability 1.

برای دانلود رایگان متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

“Weak yet strong” restrictions of Hindman’s Finite Sums Theorem∗

We present a natural restriction of Hindman’s Finite Sums Theorem that admits a simple combinatorial proof (one that does not also prove the full Finite Sums Theorem) and low computability-theoretic and proof-theoretic upper bounds, yet implies the existence of the Turing Jump, thus realizing the only known lower bound for the full Finite Sums Theorem. This is the first example of this kind. In...

متن کامل

Turing Incomparability in Scott Sets

For every Scott set F and every nonrecursive set X in F , there is a Y ∈ F such that X and Y are Turing incomparable.

متن کامل

The Veblen functions for computability theorists

We study the computability-theoretic complexity and proof-theoretic strength of the following statements: (1) “If X is a well-ordering, then so is εX ”, and (2) “If X is a well-ordering, then so is φ(α,X )”, where α is a fixed computable ordinal and φ represents the two-placed Veblen function. For the former statement, we show that ω iterations of the Turing jump are necessary in the proof and ...

متن کامل

Ordinal Analysis and the Infinite Ramsey Theorem

The infinite Ramsey theorem is known to be equivalent to the statement ‘for every set X and natural number n, the n-th Turing jump of X exists’, over RCA0 due to results of Jockusch [5]. By subjecting the theory RCA0 augmented by the latter statement to an ordinal analysis, we give a direct proof of the fact that the infinite Ramsey theorem has proof-theoretic strength εω. The upper bound is ob...

متن کامل

Image flip CAPTCHA

The massive and automated access to Web resources through robots has made it essential for Web service providers to make some conclusion about whether the "user" is a human or a robot. A Human Interaction Proof (HIP) like Completely Automated Public Turing test to tell Computers and Humans Apart (CAPTCHA) offers a way to make such a distinction. CAPTCHA is a reverse Turing test used by Web serv...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

عنوان ژورنال:
  • Ann. Pure Appl. Logic

دوره 162  شماره 

صفحات  -

تاریخ انتشار 2010