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- A strong form of König’s lemma October 21, 2017
- Prikry forcing may add a Souslin tree June 12, 2016
- The reflection principle $R_2$ May 20, 2016
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- Generalizations of Martin’s Axiom and the well-met condition January 11, 2015
- Many diamonds from just one January 6, 2015
- Happy new jewish year! September 24, 2014
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Whitehead Problem Minimal Walks Square-Brackets Partition Relations Cardinal function Large Cardinals Almost Souslin Shelah's Strong Hypothesis Jonsson cardinal Small forcing Sakurai's Bell inequality Weakly compact cardinal Singular cardinals combinatorics Prikry-type forcing Club Guessing Prevalent singular cardinals Singular coﬁnality HOD S-Space Distributive tree Axiom R Universal Sequences Nonspecial tree Forcing Axioms super-Souslin tree Hedetniemi's conjecture Kurepa Hypothesis very good scale L-space Dushnik-Miller square principles Rainbow sets PFA(S)[S] Successor of Regular Cardinal Singular Density stationary hitting Absoluteness b-scale P-Ideal Dichotomy Ostaszewski square stationary reflection Fat stationary set Cohen real Martin's Axiom Chromatic number Diamond Uniformly coherent Constructible Universe OCA incompactness Reduced Power Forcing Coherent tree Stevo Todorcevic tensor product graph Rado's conjecture polarized partition relation Mandelbrot set Almost countably chromatic Postprocessing function free Boolean algebra Rock n' Roll Parameterized proxy principle Commutative cancellative semigroups Ascent Path Luzin set weak diamond 20M14 Hindman's Theorem ccc Uniformization 11P99 Almost-disjoint famiy sap Poset Knaster 05A17 Fodor-type reflection diamond star Hereditarily Lindelöf space Chang's conjecture Fast club Erdos-Hajnal graphs Souslin Tree Selective Ultrafilter Erdos Cardinal Successor of Singular Cardinal approachability ideal middle diamond Microscopic Approach Aronszajn tree Generalized Clubs reflection principles Partition Relations Antichain square Slim tree projective Boolean algebra Non-saturation Foundations Cardinal Invariants weak square coloring number PFA xbox

# Tag Archives: Martin’s Axiom

## Generalizations of Martin’s Axiom and the well-met condition

Recall that Martin’s Axiom asserts that for every partial order $\mathbb P$ satisfying c.c.c., and for any family $\mathcal D$ of $<2^{\aleph_0}$ many dense subsets of $\mathbb P$, there exists a directed subset $G$ of $\mathbb P$ such that $G\cap … Continue reading

## Shelah’s solution to Whitehead’s problem

Whitehead problem notes in hebrew : Table of contents Chapter 0 Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 References