= Club of closure points for countable set-valued functions
{title2=$D=\{\delta:(\forall\alpha<\delta)\ B(\alpha)\subseteq\delta\}$}
For a regular uncountable <cardinal> $\lambda$ and $B:\lambda\to[\lambda]^\omega$, the <limit ordinals> closed under all earlier values of $B$ form a <club set>. Countably iterate bounds for $\bigcup_{\alpha<\gamma}B(\alpha)$ to obtain unboundedly many closure points. Regularity keeps each bound and the countable supremum below $\lambda$. Limits of closure points remain closure points.
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