### Archives

### Recent blog posts

- 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
- Prolific Souslin trees March 17, 2016
- 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
- Square principles April 19, 2014

### Keywords

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

# Category Archives: Notes

## 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

## Infinite Combinatorial Topology

Back in 2005, as a master student, I attended a course by Boaz Tsaban, entitled “Infinite Combinatorial Topology”. A friend and I decided to produce lecture notes, but in a somewhat loose sense, that is: we sometimes omit material given … Continue reading

Posted in Notes
Tagged b-scale, Cardinal function, Cardinal Invariants, Hereditarily Lindelöf space
8 Comments