Alphabeta Math

Covering Spaces and Lifting

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✓ 22 results · all verified · 4 also independently AI-judged
Every result on this page is machine-checked by a proof checker and read in full and owner-audited; the judge is an additional, independent cross-model AI review of the proofs. The 18 not AI-judged were verified by owner audit (typically over a confirmed judge false positive), not failures.
1 · Prerequisites
2 · Logical flowchart

3 · Items

Definition

Covering maps, evenly covered neighbourhoods, fibres, sheets, and trivial coverings

Definition

Maps and isomorphisms of covering spaces over a fixed base

Definition

Lifts of maps, paths, and homotopies through a covering map

Proposition

Covering maps are surjective local homeomorphisms with discrete fibres

Proposition

The cardinality of a covering fibre is locally constant and is constant on a connected base

Theorem

Existence and uniqueness of path lifts through a covering map

Theorem

Existence and uniqueness of homotopy lifts through a covering map

Corollary

The endpoint of a lifted path depends only on its endpoint-fixed homotopy class

Theorem

A covering map induces an injective homomorphism on fundamental groups

Theorem

Two lifts from a connected space that agree at one point agree everywhere

Theorem

Lifting criterion for maps from path-connected locally path-connected spaces

Definition

The pullback of a covering space along a continuous map

Proposition

Covering spaces are stable under restriction, finite products, and pullback

Proposition

A composite of covering maps is a covering when the outer covering is finite-sheeted

Definition

The monodromy right action on a covering fibre and its equivalent left-action convention

Proposition

Monodromy acts by fibre bijections, and its orbits are the intersections of path components with the fibre

Definition

Deck transformations and the deck-transformation group of a covering

Proposition

On a connected covering space, a deck transformation is determined by one point and the deck action is free

Definition

Covering-space actions by disjoint translates of neighbourhoods

Theorem

The orbit map of a covering-space action is a covering, with the acting group equal to the deck group when the total space is path-connected

Proposition

Local path-connectedness lifts and descends along covering maps

Definition

Semilocally simply connected spaces with explicit basepoint convention

Definition

Universal covering spaces

Theorem

A space admitting a universal covering is semilocally simply connected

Definition

The based path-class model and basic sets for a universal cover

Lemma

For a nonempty path-connected locally path-connected semilocally simply connected space, the path-class projection is a covering map

Theorem

Every nonempty path-connected locally path-connected semilocally simply connected space has a universal cover

Theorem

For a path-connected locally path-connected base, a universal cover maps uniquely over the base to every connected covering, and any two universal covers are uniquely isomorphic

Corollary

A connected covering of a locally path-connected simply connected space is one-sheeted and trivial

Theorem

For a nonempty path-connected total space, a covering fibre is in bijection with the right cosets of the induced fundamental-group subgroup

Theorem

For a finite-sheeted covering, the total space is compact exactly when the base is compact

Theorem

For a path-connected locally path-connected semilocally simply connected base, the deck group of a universal cover is isomorphic to the fundamental group

Sources