# Tag Archives: OCA

Nik Weaver asked for a direct proof of the fact that Todorcevic’s axiom implies the failure of CH fails. Here goes. Notation. For a set $X$, we write $[X]^2$ for the set of unordered pairs $\{ \{x,x’\}\mid x,x’\in X, x\neq … Continue reading Posted in Blog, Expository | Tagged , | 13 Comments ## Open coloring and the cardinal invariant$\mathfrak b$Nik Weaver asked for a direct proof of the fact that Todorcevic’s axiom implies the failure of CH fails. Here goes. Notation. For a set$X$, we write$[X]^2$for the set of unordered pairs$\{ \{x,x’\}\mid x,x’\in X, x\neq … Continue reading

Posted in Blog, Expository | Tagged , | 13 Comments