Noetherian type conjecture for Pixley–Roy hyperspaces

Let (X,τ)(X,\tau) be a topological space, and let PR(X)=[X]<ωPR(X)=[X]^{<\omega} be the set of finite subsets of XX equipped with the Pixley–Roy topology, whose basic open sets are

[F,U]={GPR(X):FGU},[F,U]=\{G\in PR(X):F\subset G\subset U\},

for FPR(X)F\in PR(X) and UτU\in\tau. Here NtNt denotes the Noetherian type of a topological space. Pixley–Roy hyperspace conjecture.

Nt(PR(X))Nt(X).Nt(PR(X))\leq Nt(X).

This conjecture was tested on several examples of spaces. The analogous inequality Nt(Exp(X))Nt(X)Nt(\operatorname{Exp}(X))\leq Nt(X) is known for the Vietoris hyperspace of finite subsets, but the authors identify the Pixley–Roy construction as a possible additional exception to the usual computability of cardinal functions.

Sources & referencesView supporting material

Primary source

Santi Spadaro, “On two topological cardinal invariants of an order-theoretic flavour”, arXiv:1212.5725 (2012).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.