2025-03-01 14:26:36 +01:00

554 B

Definition

Given F \subset \wp(X). The weakest topology on X that contains F is the intersection of all the Topology that contains F. This is a Topology, and consists of \emptyset, X, and all unions of finite intersections of members from F.

[!example] F \subset \tau \textvisiblespace \cap \tau \ni U_{i} \implies U_{i} \in \tau \implies \cap_{i \in F} \; U_{i} \in \tau \implies \cap U_{i} \in \cap_{F \in \tau} \;\tau

x_{i} \to x \exists j such that x_{i} = x, \; i \geq j.