DefinitionDefinition: Literature-sourcedProof: Not applicablejudge pass (gpt-5.6-terra)audited 2026-09-01

How statement and proof provenance work

The first chip identifies the source of the statement or construction; the second identifies the source of its local proof or verification.

Literature-sourced: the exact statement appears in a cited source; only wording and notation differ.
AI-adapted: a semantically identical restatement of literature-sourced material, modulo indexing, notation, and boundary cases adopted by the library.
AI-generated: a genuinely novel statement formulated by AI, with no source for the claim itself.

These labels describe origin, not correctness: citations and verification chips remain separate evidence.

A subgroup is separable when it is closed in the profinite topology, and a group is LERF when every finitely generated subgroup is separable

Definition

Let $G$ be a group with its profinite topology and let $H \leq G$ (The profinite topology on a group uses finite-index normal subgroups as an identity-neighbourhood basis, Subgroup). The subgroup $H$ is separable when it is closed in that topology; equivalently, for every $g \in G ∖ H$ there is a finite-index normal subgroup $N ⊴ G$ such that $H \subseteq H N$ but $g \notin H N$ .

The group $G$ is LERF when every finitely generated subgroup of $G$ is separable.

Depends on

Used by

Every finitely generated free group is subgroup separable Theorem

Dependency tree · two levels

8 results within two dependency steps of this one, each drawn at its shortest distance from it. An arrow runs from a result to what uses it, so the chart reads left to right and ends at this result, which carries a heavier outline. Every node is a link to that result. Click elsewhere on the chart to enlarge it.

Sources

Brian Osserman, Math 6112 notes on inverse limits and profinite groups (standard reference, not scraped)
H. W. Lenstra, Profinite groups and Galois groups (standard reference, not scraped)