A consistency result on weak reflection

نویسندگان

  • James Cummings
  • Saharon Shelah
چکیده

In this paper we study the notion of strong non-reflection, and its contrapositive weak reflection. We say θ strongly non-reflects at λ iff there is a function F : θ −→ λ such that for all α < θ with cf(α) = λ there is C club in α such that F 1 C is strictly increasing. We prove that it is consistent to have a cardinal θ such that strong non-reflection and weak reflection each hold on an unbounded set of cardinals less than θ. 1

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

Diamonds, Compactness, and Measure Sequences

We establish the consistency of the failure of the diamond principle on a cardinal κ which satisfies a strong simultaneous reflection property. The result is based on an analysis of Radin forcing, and further leads to a characterization of weak compactness of κ in a Radin generic extension.

متن کامل

Reflections about Reflection

In the line of a syntactic treatment of modalities, many proposals have been presented consisting in an extension of a logic calculus with a meta-language for expressing facts about terms and sentences, and with an axiomatization of provability. These proposals differ in the use of the inference rules used to link the object level and meta-level theories; the formulation of these reflection rul...

متن کامل

Hierarchies of Forcing Axioms, the Continuum Hypothesis and Square Principles

I analyze the hierarchies of the bounded and the weak bounded forcing axioms, with a focus on their versions for the class of subcomplete forcings, in terms of implications and consistency strengths. For the weak hierarchy, I provide level-by-level equiconsistencies with an appropriate hierarchy of partially remarkable cardinals. I also show that the subcomplete forcing axiom implies Larson’s o...

متن کامل

Canonical structure in the universe of set theory: part two

We prove a number of consistency results complementary to the ZFC results from our paper [4]. We produce examples of non-tightly stationary mutually stationary sequences, sequences of cardinals on which every sequence of sets is mutually stationary, and mutually stationary sequences not concentrating on a fixed cofinality. We also give an alternative proof for the consistency of the existence o...

متن کامل

Weak reflection at the successor of a singular cardinal

The notion of stationary reflection is one of the most important notions of combinatorial set theory. We investigate weak reflection, which is, as its name suggests, a weak version of stationary reflection. Our main result is that modulo a large cardinal assumption close to 2hugeness, there can be a regular cardinal κ such that the first cardinal

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 1995