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### Recent blog posts

- Prikry forcing may add a Souslin tree June 12, 2016
- The reflection principle $R_2$ May 20, 2016
- Prolific Souslin trees March 17, 2016
- Genearlizations 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
- Square principles April 19, 2014
- Partitioning the club guessing January 22, 2014

### Keywords

Successor of Regular Cardinal Ascent Path Cardinal Invariants Universal Sequences Whitehead Problem Microscopic Approach polarized partition relation Prevalent singular cardinals Commutative cancellative semigroups Hereditarily Lindelöf space L-space diamond star OCA xbox Forcing Uniformization stationary reflection Almost Souslin Souslin Tree Fat stationary set approachability ideal Partition Relations reflection principles incompactness Erdos Cardinal Large Cardinals Constructible Universe Foundations weak diamond Fast club Kurepa Hypothesis stationary hitting Hedetniemi's conjecture Forcing Axioms Coherent tree tensor product graph b-scale P-Ideal Dichotomy PFA Almost-disjoint famiy Minimal Walks HOD Poset Ostaszewski square Jonsson cardinal Singular Density Aronszajn tree Stevo Todorcevic Singular Cofinality Non-saturation Reduced Power Axiom R Fodor-type reflection Club Guessing Martin's Axiom 11P99 Antichain square 05A17 Cardinal function Slim tree weak square Rock n' Roll Selective Ultrafilter Prikry-type forcing Hindman's Theorem free Boolean algebra Chromatic number Almost countably chromatic middle diamond Singular cardinals combinatorics Erdos-Hajnal graphs Weakly compact cardinal Sakurai's Bell inequality Singular coﬁnality Knaster Chang's conjecture Mandelbrot set projective Boolean algebra Dushnik-Miller Absoluteness Square-Brackets Partition Relations very good scale sap Parameterized proxy principle ccc PFA(S)[S] Shelah's Strong Hypothesis Successor of Singular Cardinal Diamond Rado's conjecture Cohen real S-Space Small forcing 05D10 20M14 Generalized Clubs coloring number Rainbow sets

# Tag Archives: Whitehead Problem

## Jensen’s diamond principle and its relatives

This is chapter 6 in the book Set Theory and Its Applications (ISBN: 0821848127). Abstract: We survey some recent results on the validity of Jensen’s diamond principle at successor cardinals. We also discuss weakening of this principle such as club … 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