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ZFC construction Precaliber free Boolean algebra Uniformization SNR Postprocessing function square principles Slim tree Diamond for trees Forcing Axioms Reflecting stationary set Sierpinski's onto mapping principle very good scale Almost countably chromatic Iterated forcing nonmeager set Reduced Power specializable Souslin tree Non-saturation HOD Commutative cancellative semigroups Strongly Luzin set positive partition relation Kurepa Hypothesis transformations Sigma-Prikry Rock n' Roll Poset super-Souslin tree regressive Souslin tree Partition Relations Mandelbrot set full tree Shelah's Strong Hypothesis Hedetniemi's conjecture Minimal Walks Selective Ultrafilter middle diamond indecomposable ultrafilter Hindman's Theorem Souslin Tree Square-Brackets Partition Relations Closed coloring Fodor-type reflection Prevalent singular cardinals Sakurai's Bell inequality Dowker space AIM forcing projective Boolean algebra weak Kurepa tree Club Guessing Subtle tree property Large Cardinals Coherent tree unbounded function Well-behaved magma Erdos Cardinal Greatly Mahlo Fat stationary set Constructible Universe strongly bounded groups PFA PFA(S)[S] Ascent Path Filter reflection Nonspecial tree Whitehead Problem Erdos-Hajnal graphs sap Cohen real P-Ideal Dichotomy Commutative projection system Cardinal Invariants countably metacompact Subadditive Knaster and friends Absoluteness Lipschitz reduction xbox Chang's conjecture S-Space Axiom R Diamond-sharp Generalized Clubs O-space Respecting tree coloring number OCA Amenable C-sequence Uniformly coherent Countryman line Knaster weak diamond Distributive tree Ostaszewski square Ineffable cardinal Generalized descriptive set theory Cardinal function Martin's Axiom club_AD Parameterized proxy principle polarized partition relation Luzin set tensor product graph Strong coloring Subnormal ideal Hereditarily Lindelöf space Was Ulam right? Intersection model stick incompactness b-scale approachability ideal Singular cardinals combinatorics Microscopic Approach square Antichain Local Club Condensation. ccc Vanishing levels reflection principles Strongly compact cardinal Rado's conjecture Almost Souslin C-sequence Aronszajn tree Rainbow sets Subtle cardinal Weakly compact cardinal Fast club Uniformly homogeneous Prikry-type forcing Foundations Successor of Singular Cardinal higher Baire space L-space Open Access Singular Density stationary hitting stationary reflection Forcing Universal Sequences Dushnik-Miller Singular cofinality weak square Analytic sets Almost-disjoint family GMA Chromatic number Ramsey theory over partitions Ulam matrix Small forcing free Souslin tree Diamond Jonsson cardinal diamond star Successor of Regular Cardinal 54G20
Tag Archives: PFA
Square principles
Since the birth of Jensen’s original Square principle, many variations of the principle were introduced and intensively studied. Asaf Karagila suggested me today to put some order into all of these principles. Here is a trial. Definition. A square principle … Continue reading
PFA and the tree property at
Recall that a poset
