Space S000202

Metric fan with ω\omega-many spines

The subspace of Euclidean Plane R2\mathbb R^2 defined by X={0,0}{1m,1mn:m,nZ+}X=\{\langle 0,0\rangle\}\cup\{\langle \frac{1}{m},\frac{1}{mn} \rangle :m,n\in\mathbb Z^+\}

Equivalently, a classical special case of the filter fans defined in zbMATH 1339.54022: the set X={}ω2X=\{\infty\}\cup\omega^2 with ω2\omega^2 discrete and neighborhoods of \infty containing all but finitely-many rows of ω2\omega^2.

Compare with the finer topology of Sequential fan with ω\omega-many spines.

S202: Metric fan with $\omega$-many spines | π-Base