scholarly journals The largest countable inductive set is a mouse set

1999 ◽  
Vol 64 (2) ◽  
pp. 443-459 ◽  
Author(s):  
Mitch Rudominer
Keyword(s):  
Consistency Strength ◽  
Woodin Cardinals ◽  
Inner Model ◽  
Theoretic Proof

AbstractLet κℝ be the least ordinal κ such that Lκ (ℝ) is admissible. Let A = {x ϵ ℝ ∣ (∃α < κℝ) such that x is ordinal definable in Lα (ℝ)}. It is well known that (assuming determinacy) A is the largest countable inductive set of reals. Let T be the theory: ZFC − Replacement + “There exists ω Woodin cardinals which are cofinal in the ordinals.” T has consistency strength weaker than that of the theory ZFC + “There exists ω Woodin cardinals”, but stronger than that of the theory ZFC + “There exists n Woodin Cardinals”, for each n ϵ ω. Let M be the canonical, minimal inner model for the theory T. In this paper we show that A = ℝ ∩ M. Since M is a mouse, we say that A is a mouse set. As an application, we use our characterization of A to give an inner-model-theoretic proof of a theorem of Martin which states that for all n, every real is in A.

scholarly journals THE CONSISTENCY STRENGTH OF LONG PROJECTIVE DETERMINACY

2019 ◽  
Vol 85 (1) ◽  
pp. 338-366 ◽  
Author(s):  
JUAN P. AGUILERA ◽  
SANDRA MÜLLER
Keyword(s):  
Set Theory ◽  
Consistency Strength ◽  
Axiom Of Determinacy ◽  
Woodin Cardinals ◽  
Inner Model ◽  
Image Position ◽  
Woodin Cardinal

AbstractWe determine the consistency strength of determinacy for projective games of length ω2. Our main theorem is that $\Pi _{n + 1}^1 $-determinacy for games of length ω2 implies the existence of a model of set theory with ω + n Woodin cardinals. In a first step, we show that this hypothesis implies that there is a countable set of reals A such that Mn (A), the canonical inner model for n Woodin cardinals constructed over A, satisfies $$A = R$$ and the Axiom of Determinacy. Then we argue how to obtain a model with ω + n Woodin cardinal from this.We also show how the proof can be adapted to investigate the consistency strength of determinacy for games of length ω2 with payoff in $^R R\Pi _1^1 $ or with σ-projective payoff.

scholarly journals Ramsey-like cardinals II

2011 ◽  
Vol 76 (2) ◽  
pp. 541-560 ◽  
Author(s):  
Victoria Gitman ◽  
P. D. Welch
Keyword(s):  
Upper Bound ◽  
Large Cardinals ◽  
Large Cardinal ◽  
Core Model ◽  
Consistency Strength ◽  
The Core ◽  
Countable Ordinal ◽  
Elementary Embeddings ◽  
Remarkable Cardinals

AbstractThis paper continues the study of the Ramsey-like large cardinals introduced in [5] and [14]. Ramsey-like cardinals are defined by generalizing the characterization of Ramsey cardinals via the existence of elementary embeddings. Ultrafilters derived from such embeddings are fully iterable and so it is natural to ask about large cardinal notions asserting the existence of ultrafilters allowing only α-many iterations for some countable ordinal α. Here we study such α-iterable cardinals. We show that the α-iterable cardinals form a strict hierarchy for α ≤ ω1, that they are downward absolute to L for , and that the consistency strength of Schindler's remarkable cardinals is strictly between 1-iterable and 2-iterable cardinals.We show that the strongly Ramsey and super Ramsey cardinals from [5] are downward absolute to the core model K. Finally, we use a forcing argument from a strongly Ramsey cardinal to separate the notions of Ramsey and virtually Ramsey cardinals. These were introduced in [14] as an upper bound on the consistency strength of the Intermediate Chang's Conjecture.

scholarly journals An inner model theoretic proof of Becker’s theorem

2019 ◽  
Vol 58 (7-8) ◽  
pp. 999-1003
Author(s):  
Grigor Sargsyan
Keyword(s):  
Inner Model ◽  
Theoretic Proof

STRUCTURE THEORY OFL(ℝ,μ) AND ITS APPLICATIONS

2015 ◽  
Vol 80 (1) ◽  
pp. 29-55 ◽  
Author(s):  
NAM TRANG
Keyword(s):  
Structure Theory ◽  
Consistency Strength ◽  
Woodin Cardinals

AbstractIn this paper, we explore the structure theory ofL(ℝ,μ) under the hypothesisL(ℝ,μ) ⊧ “AD +μis a normal fine measure on” and give some applications. First we show that “ ZFC + there existω2Woodin cardinals”1has the same consistency strength as “ AD +ω1is ℝ-supercompact”. During this process we show that ifL(ℝ,μ) ⊧ AD then in factL(ℝ,μ) ⊧ AD+. Next we prove important properties ofL(ℝ,μ) including Σ1-reflection and the uniqueness ofμinL(ℝ,μ). Then we give the computation of full HOD inL(ℝ,μ). Finally, we use Σ1-reflection and ℙmaxforcing to construct a certain ideal on(or equivalently onin this situation) that has the same consistency strength as “ZFC+ there existω2Woodin cardinals.”

Weak partition relations and measurability

1986 ◽  
Vol 51 (1) ◽  
pp. 33-38
Author(s):  
Mitchell Spector
Keyword(s):  
Measurable Cardinal ◽  
Order Type ◽  
Large Cardinal ◽  
Partition Relation ◽  
Consistency Strength ◽  
Partition Relations ◽  
Inner Model ◽  
Increasing Function ◽  
Natural Way

The concept of "partition relation" has proven to be extremely important in the development of the theory of large cardinals. This is due in good part to the fact that the ordinal numbers which appear as parameters in partition relations provide a natural way to define a detailed hierarchy of the corresponding large cardinal axioms. In particular, the study of cardinals satisfying Ramsey-Erdös-style partition relations has yielded a great number of very interesting large cardinal axioms which lie in strength strictly between inaccessibility and measurability. It is the purpose of this paper to show that this phenomenon does not occur if we use infinite exponent partition relations; no such partition relation has consistency strength strictly between inaccessibility and measurability. We also give a complete determination of which infinite exponent partition relations hold, assuming that there is no inner model of set theory with a measurable cardinal.Our notation is standard. If F is a function and x is a set, then F″x denotes the range of F on x. If X is a set of ordinals and α is an ordinal, then [X]α is the collection of all subsets of X of order type α. We identify a member of [X]α with a strictly increasing function from α to X. If p ∈ [X]α and q ∈ [α]β, then the composition of p with q, which we denote pq, is a member of [X]β.

Determinacy in L(ℝ, μ)

2014 ◽  
Vol 14 (01) ◽  
pp. 1450006 ◽  
Author(s):  
Nam Trang
Keyword(s):  
Woodin Cardinals

Assume V = L(ℝ, μ) ⊨ ZF + DC + Θ > ω2 + μ is a normal fine measure on 𝒫ω1(ℝ). We analyze what sets of reals are determined and in fact show that L(ℝ, μ) ⊨ AD . This arguably gives the most optimal characterization of AD in L(ℝ, μ). As a consequence of this analysis, we obtain the equiconsistency of the theories: "ZFC + there are ω2 Woodin cardinals" and "ZF + DC + Θ > ω2 + there is a normal fine measure on 𝒫ω1(ℝ)".

Changing cardinal invariants of the reals without changing cardinals or the reals

1998 ◽  
Vol 63 (2) ◽  
pp. 593-599 ◽  
Author(s):  
Heike Mildenberger
Keyword(s):  
Measurable Cardinal ◽  
Consistency Strength ◽  
Cardinal Invariants ◽  
Inner Model ◽  
Cichoń’S Diagram

AbstractWe show: The procedure mentioned in the title is often impossible. It requires at least an inner model with a measurable cardinal. The consistency strength of changing and from a regular κ to some regular δ < κ is a measurable of Mitchell order δ. There is an application to Cichoń's diagram.

Proper forcing and L(ℝ)

2001 ◽  
Vol 66 (2) ◽  
pp. 801-810 ◽  
Author(s):  
Itay Neeman ◽  
Jindřich Zapletal
Keyword(s):  
Large Cardinals ◽  
Large Cardinal ◽  
Consistency Strength ◽  
Woodin Cardinals ◽  
Proper Forcing

AbstractWe present two ways in which the model L(ℝ) is canonical assuming the existence of large cardinals. We show that the theory of this model, with ordinal parameters, cannot be changed by small forcing: we show further that a set of ordinals in V cannot be added to L(ℝ) by small forcing. The large cardinal needed corresponds to the consistency strength of ADL(ℝ): roughly ω Woodin cardinals.

Proper Forcing and Remarkable Cardinals

2000 ◽  
Vol 6 (2) ◽  
pp. 176-184 ◽  
Author(s):  
Ralf-Dieter Schindler
Keyword(s):  
Measurable Cardinal ◽  
Large Cardinal ◽  
Exact Formulation ◽  
Axiom Of Determinacy ◽  
Slow Pace ◽  
Woodin Cardinals ◽  
Inner Model ◽  
Proper Forcing ◽  
Remarkable Cardinals ◽  
The Universe

The present paper investigates the power of proper forcings to change the shape of the universe, in a certain well-defined respect. It turns out that the ranking among large cardinals can be used as a measure for that power. However, in order to establish the final result I had to isolate a new large cardinal concept, which I dubbed “remarkability.” Let us approach the exact formulation of the problem—and of its solution—at a slow pace.Breathtaking developments in the mid 1980s found one of its culminations in the theorem, due to Martin, Steel, and Woodin, that the existence of infinitely many Woodin cardinals with a measurable cardinal above them all implies that AD, the axiom of determinacy, holds in the least inner model containing all the reals, L(ℝ) (cf. [6[, p. 91). One of the nice things about AD is that the theory ZF + AD + V = L(ℝ) appears as a choiceless “completion” of ZF in that any interesting question (in particular, about sets of reals) seems to find an at least attractive answer in that theory (cf., for example, [5] Chap. 6). (Compare with ZF + V = L!) Beyond that, AD is very canonical as may be illustrated as follows.Let us say that L(ℝ) is absolute for set-sized forcings if for all posets P ∈ V, for all formulae ϕ, and for all ∈ ℝ do we have thatwhere is a name for the set of reals in the extension.

UNIVERSALLY BAIRE SETS AND GENERIC ABSOLUTENESS

2017 ◽  
Vol 82 (4) ◽  
pp. 1229-1251
Author(s):  
TREVOR M. WILSON
Keyword(s):  
Measurable Cardinal ◽  
Consistency Strength ◽  
Woodin Cardinals ◽  
Generic Absoluteness ◽  
Relative Consistency ◽  
Consistency Results ◽  
High Consistency ◽  
Image Position ◽  
General Method

AbstractWe prove several equivalences and relative consistency results regarding generic absoluteness beyond Woodin’s ${\left( {{\bf{\Sigma }}_1^2} \right)^{{\rm{u}}{{\rm{B}}_\lambda }}}$ generic absoluteness result for a limit of Woodin cardinals λ. In particular, we prove that two-step $\exists ^&#x211D; \left( {{\rm{\Pi }}_1^2 } \right)^{{\rm{uB}}_\lambda } $ generic absoluteness below a measurable limit of Woodin cardinals has high consistency strength and is equivalent, modulo small forcing, to the existence of trees for ${\left( {{\bf{\Pi }}_1^2} \right)^{{\rm{u}}{{\rm{B}}_\lambda }}}$ formulas. The construction of these trees uses a general method for building an absolute complement for a given tree T assuming many “failures of covering” for the models $L\left( {T,{V_\alpha }} \right)$ for α below a measurable cardinal.

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