Do closed-ultrafilter-limits keep cov(N) small?
Determine whether finite-support iterations of ccc forcings whose iterands have closed-ultrafilter-limits (c-uf-limits) can keep the covering number of the null ideal cov(N) small; equivalently, ascertain whether c-uf-limit methods provide the "inside" preservation needed to force C_{[A]^{<θ} ≤_T Cn and thus ensure cov(N) ≤ θ in the resulting model.
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In the left side of Cicho n's diagram, many cardinal invariants are either below e or above e_{ubd} (hence closed-ultrafilter-limits do not keep them small) and a remaining candidate is N. However, not only it is unclear whether c-uf-limits keep it small, but also even if they did, it would be unclear whether there would be an application since most of the known forcings with c-uf-limits are either σ-centered or sub-random, which keep N small without resorting to c-uf-limits.