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Search options questions only not deleted user 82843
3 votes
1 answer
764 views

Is tree property inconsistent with Berkeley cardinals in the absence of Axiom of Choice?

On one hand due to Kunen's inconsistency theorem it is known that within $\sf ZF$, large cardinal axioms beyond Reinhardt cardinal are inconsistent with $\sf AC$. Also some recent results of Bagaria, …
Morteza Azad's user avatar
5 votes
1 answer
399 views

Can Woodin's fast function forcing kill Shelah cardinals?

Definition 1. An uncountable cardinal $\kappa$ is Shelah if for every function $f:\kappa\rightarrow \kappa$ there exists a transitive class $M$ and a non-trivial elementary embedding $j:V\rightarrow M …
Morteza Azad's user avatar
2 votes
1 answer
636 views

On the Actual Potential of Virtual Large Cardinals

Virtual large cardinals belong to a relatively new breed of strong axioms of infinity. They often appear as statements of the following form: Definition. Suppose $A$ is a large cardinal property c …
Morteza Azad's user avatar
8 votes
2 answers
308 views

Does fast function forcing really have $\kappa$-Knaster property?

I ran into a claim concerning Woodin's fast function forcing in the following paper of Apter and Cummings which sounds no right to me: A. Apter, J. Cummings, Blowing up the power set of the least meas …
Morteza Azad's user avatar
5 votes
1 answer
673 views

What are examples of non-equivalent virtualizations of a large cardinal?

This is a follow up to my previous question concerning virtual large cardinals, that are generally weaker axioms of infinity obtained from ordinary large cardinals through the so-called virtualization …
Morteza Azad's user avatar
7 votes
2 answers
761 views

Which large cardinals have a Matryoshka characterization?

What on Earth do Russian Matryoshka dolls have in common with large cardinal axioms?! Well, the answer lies in Jónsson algebras! Here is how: As illustrated in the pictures, a Matryoshka set is a self …
Morteza Azad's user avatar
2 votes
1 answer
385 views

Strong Total Failures vs. Weak Instances of the Generalized Continuum Hypothesis

The exponentiation operator inflicts a subtle information loss on the transfinite numerical equations, pretty similar to the case of $a^2=b^2 \nRightarrow a=b$ in real numbers. In fact, for the infini …
Morteza Azad's user avatar
13 votes
3 answers
1k views

Cops, Robbers and Cardinals: The Infinite Manhunt

Cops & Robbers is a certain pursuit-evasion game between two players, Alice and Bob. Alice is in charge of the Justice Bureau, which controls one or more law enforcement officers, the cops. Bob contro …
Morteza Azad's user avatar
9 votes
1 answer
595 views

On the Large Cardinal Strength of Normal Moore Space Conjecture

In his seminal 1937 paper, Jones [1] proved the following result about Moore spaces: Theorem. (Jones) If $2^{\aleph_0}<2^{\aleph_1}$ then all separable normal Moore spaces are metrizable. Then h …
Morteza Azad's user avatar
3 votes
1 answer
328 views

What is the consistency strength of non-existence of outer automorphisms of Calkin algebra?

The Calkin algebra $C(H)$ is the quotient of $B(H)$, the ring of bounded linear operators on a separable infinite-dimensional Hilbert space $H$, by the ideal $K(H)$ of compact operators. In 1977, Br …
Morteza Azad's user avatar
5 votes
2 answers
533 views

Statements that Could be Forced by Ultrapowers

Ultrapower of a structure is a very flexible mathematical creature in comparison with the ground structure and its ordinary products. Depending on the nature of ground structure and the good propertie …
Morteza Azad's user avatar
3 votes
1 answer
442 views

A Question on HOD, V and GCH

The theorem 1.1 of the following paper: Mohammad Golshani, V, HOD, and the GCH, Journal of Symbolic Logic. states that: Theorem: Assume $V\models ZFC+GCH+~\text{There exists a}~(\kappa+4)-\text{str …
Morteza Azad's user avatar
19 votes
2 answers
8k views

The Ultimate L in a Nutshell: On Descriptive Articles

Everybody who catches a fleeting glimpse of Woodin's central papers on Ultimate $L$ (i.e. Suitable Extender Models I & II), admits that they aren't so tempting for lazy readers who don't like to deal …
Morteza Azad's user avatar
31 votes
8 answers
3k views

On independence and large cardinal strength of physical statements

The present post is intended to tackle the possible interactions of two bizarre realms of extremely large and extremely small creatures, namely large cardinals and quantum physics. Maybe after all tho …
Morteza Azad's user avatar