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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
- 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

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

# Tag Archives: projective Boolean algebra

## Openly generated Boolean algebras and the Fodor-type reflection principle

Joint work with Sakaé Fuchino. Abstract: We prove that the Fodor-type Reflection Principle (FRP) is equivalent to the assertion that any Boolean algebra is openly generated if and only if it is $\aleph _2$-projective. Previously it was known that this … Continue reading