Monotone normality and nabla products
Monotone normality and nabla products
Roitman’s combinatorial principle $\Delta $ is equivalent to monotone normality of the nabla product, $\nabla (\omega +1)^\omega $. If $\{ X_n : n\in \omega \}$ is a family of metrizable spaces and $\nabla _n X_n$ is monotonically normal, then $\nabla