On a σ-ideal of compact sets

نویسنده

  • Tamás Mátrai
چکیده

We recall from [10] a Gδ σ-ideal of compact subsets of 2 ω and prove that it is not Tukey reducible to the ideal I1/n = {H ⊆ ω : ∑ h∈H 1/h <∞}. This result answers a question of S. Solecki and S. Todorčević in the negative.

برای دانلود 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

More Cofinal Types of Definable Directed Orders

We study the cofinal diversity of analytic p-ideals and analytic relative σ-ideals of compact sets. We prove that the σ-ideal of compact meager sets is not cofinally simpler than the asymptotic density zero ideal; this concludes the study of the cofinal types of classical analytic ideals. We obtain this result by using a Ramsey-type partition calculus, which allows us to capture the relevant co...

متن کامل

A Gδ Ideal of Compact Sets Strictly above the Nowhere Dense Ideal in the Tukey Order

We prove that there is a Gδ σ-ideal of compact sets which is strictly above NWD in the Tukey order. Here NWD is the collection of all compact nowhere dense subsets of the Cantor set. This answers a question of Louveau and Veličković asked in [4].

متن کامل

Trichotomies for ideals of compact sets

We prove several trichotomy results for ideals of compact sets. Typically, we show that a “sufficiently rich” universally Baire ideal is either Π3-hard, or Σ3-hard, or else a σ-ideal.

متن کامل

σ-sporadic prime ideals and superficial elements

Let $A$ be a Noetherian ring, $I$ be an ideal of $A$ and $sigma$ be a semi-prime operation, different from the identity map on the set of all ideals of $A$. Results of Essan proved that the sets of associated prime ideals of $sigma(I^n)$, which denoted by $Ass(A/sigma(I^n))$, stabilize to $A_{sigma}(I)$. We give some properties of the sets $S^{sigma}_{n}(I)=Ass(A/sigma(I^n))setminus A_{sigma}(I...

متن کامل

Certain subalgebras of Lipschitz algebras of infinitely differentiable functions and their maximal ideal spaces

We study an interesting class of Banach function algebras of innitely dierentiable functions onperfect, compact plane sets. These algebras were introduced by Honary and Mahyar in 1999, calledLipschitz algebras of innitely dierentiable functions and denoted by Lip(X;M; ), where X is aperfect, compact plane set, M = fMng1n=0 is a sequence of positive numbers such that M0 = 1 and(m+n)!Mm+n ( m!Mm)...

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

برای دانلود 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

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2009