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Related papers: On $\omega_3$-chains in P($\omega_1$) mod finite

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We show that the forcing axiom for countably compact, $\omega_2$-Knaster, well-met posets is inconsistent. This is supplemental to an inconsistency result of Shelah and sets a new limit to the generalization of Martin's Axiom to the stage…

Logic · Mathematics 2020-08-05 Stevo Todorčević , Shihao Xiong

We consider $(<\lambda)$-support iterations of a version of $(<\lambda)$-strategically complete $\lambda^+$-c.c. definable forcing notions along partial orders. We show that such iterations can be corrected to yield an analog of a result by…

Logic · Mathematics 2024-11-14 Haim Horowitz , Saharon Shelah

In this short note, we shall prove some observations regarding the connection between indestructible $\omega_1$-guessing models and the $\omega_1$-approximation property of forcing notions.

Logic · Mathematics 2022-02-18 Rahman Mohammadpour

We deal with an iteration theorem of forcing notion with a kind of countable support of nice enough forcing notion which is proper aleph_2-c.c. forcing notions. We then look at some special cases (Q_D 's preceded by random forcing).

Logic · Mathematics 2007-05-23 Saharon Shelah

We analyse the Boolean-valued random forcing $B_{M,\Omega}$ in bounded arithmetics developed in Krajicek (Forcing with random variables and proof complexity, vol. 382, Cambridge University Press, 2011) from the perspective of the forcing in…

Logic · Mathematics 2026-03-12 Radek Honzik

In this paper, we derive recurrence relations of forcing polynomials for monotonic CHS and the other is CHS with one turning.

Combinatorics · Mathematics 2021-12-01 Shuang Zhao

The modal logic of forcing arises when one considers a model of set theory in the context of all its forcing extensions, interpreting necessity as "in all forcing extensions" and possibility as "in some forcing extension". In this modal…

Logic · Mathematics 2012-07-26 Joel David Hamkins , George Leibman , Benedikt Löwe

For $f,g\in\omega^\omega$ let $c^\forall_{f,g}$ be the minimal number of uniform $g$-splitting trees needed to cover the uniform $f$-splitting tree, i.e., for every branch $\nu$ of the $f$-tree, one of the $g$-trees contains $\nu$. Let…

Logic · Mathematics 2012-01-04 Jakob Kellner , Saharon Shelah

We prove a variation of Easton's lemma for strongly proper forcings, and use it to prove that, unlike the stronger principle $\textsf{IGMP}$, $\textsf{GMP}$ together with $2^\omega \le \omega_2$ is consistent with the existence of an…

Logic · Mathematics 2019-02-20 Sean Cox , John Krueger

A set $A$ of integers is called total if there is an algorithm which, given an enumeration of $A$, enumerates the complement of $A$, and called cototal if there is an algorithm which, given an enumeration of the complement of $A$,…

Logic · Mathematics 2017-02-10 Takayuki Kihara

We present a method which forces the failure of $\Pi^1_3$ and $\Sigma^1_3$-separation, while $\mathsf{MA} (\mathcal{I}$) holds, for $\mathcal{I}$ the family of indestructible ccc forcings. This shows that, in contrast to the assumption…

Logic · Mathematics 2025-11-05 Stefan Hoffelner

We describe a formalization of forcing using Boolean-valued models in the Lean 3 theorem prover, including the fundamental theorem of forcing and a deep embedding of first-order logic with a Boolean-valued soundness theorem. As an…

Logic in Computer Science · Computer Science 2019-04-25 Jesse Michael Han , Floris van Doorn

The Proper Forcing Axiom implies that compact Hausdorff spaces are either first-countable or contain a converging $\omega_1$-sequence.

General Topology · Mathematics 2022-01-25 Alan Dow , Klaas Pieter Hart

In this paper, we study Markov chains (MC) on topological spaces within the framework of the operator approach. We extend the Markov operator from the space of countably additive measures to the space of finitely additive measures. Cesaro…

Probability · Mathematics 2023-01-04 Alexander Zhdanok

We show that $\mathsf{PFA}$ (Proper Forcing Axiom) implies that adding any number of Cohen subsets of $\omega$ will not add an $\omega_2$-Aronszajn tree or a weak $\omega_1$-Kurepa tree, and moreover no $\sigma$-centered forcing can add a…

Logic · Mathematics 2022-08-05 Radek Honzik , Chris Lambie-Hanson , Šárka Stejskalová

Lightweight, source-to-source transformation approaches to implementing MCMC for probabilistic programming languages are popular for their simplicity, support of existing deterministic code, and ability to execute on existing fast runtimes.…

Artificial Intelligence · Computer Science 2015-09-09 Daniel Ritchie , Andreas Stuhlmüller , Noah D. Goodman

Fix a finite group $G$. We study the computational complexity of counting problems of the following flavor: given a group $\Gamma$, count the number of homomorphisms $\Gamma \to G$. Our first result establishes that this problem is…

Group Theory · Mathematics 2026-04-22 Eric Samperton , Armin Weiß

The countable condensation on a linear order $L$ is the equivalence relation $\sim_\omega$ defined by declaring $x \sim_\omega y$ when the set of points between $x$ and $y$ is countable. We characterize the linear orders $L$ that condense…

Logic · Mathematics 2025-09-19 Jennifer Brown , Ricardo Suárez

This is an expository paper about several sophisticated forcing techniques closely related to standard finite support iterations of ccc partial orders. We focus on the four topics of ultrapowers of forcing notions, iterations along…

Logic · Mathematics 2022-02-03 Joerg Brendle

We introduce an iteration of forcing notions satisfying the countable chain condition with minimal damage to a strong coloring. Applying this method, we prove that Martin's axiom is strictly stronger than its restriction to forcing notions…

Logic · Mathematics 2024-06-21 Yinhe Peng