G-delta subset

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This article defines a property over pairs of a topological space and a subspace, or equivalently, properties over subspace embeddings (viz, subsets) in topological spaces

Definition

A subset of a topological space is termed a G_\delta subset if it is expressible as a countable intersection of open subsets.

Relation with other properties

Stronger properties

Related properties

There are related notions captured in the G hierarchy and F hierarchy