The Cartesian product of any family of $W$-spaces is $\kappa$-Fréchet-Urysohn

Abstract

In this note, we prove that an arbitrary product of $W$-spaces is a $\kappa$-Fréchet-Urysohn space. We also show that the boundary tightness of a product $X\times Y$ is at most $\kappa$ provided that $X$ is compact with tightness $t(X)\le \kappa$ and $Y$ has boundary tightness $tb(Y)\le \kappa$. The first result fully resolves, and the second partially addresses, two questions recently raised by Tkachuk.