In mathematics, a double cover or double covering may refer to:
- Double cover (topology), a two-to-one mapping from one topological space to another. Frequently occurring special cases include
- The orientable double cover of a non-orientable manifold.
- The bipartite double cover of an undirected graph G, formed by the graph tensor product G ×K2.
- A double covering group of a topological group such as a Lie group, a group extension of index two formed by a topological double cover. A double cover may also be used to refer to non-topological group extensions of index two, for instance extensions of finite groups.
- Cycle double cover, a collection of cycles in a graph that together include each edge twice. The cycle double cover conjecture is the unproven assertion that every bridgeless graph has a cycle double cover.
Double coverage may also refer to:
- Double coverage, a defensive strategy in American football, basketball, and other sports
- Being covered by more than one health insurance plan
Famous quotes containing the words double and/or cover:
“since I see
Your double heart,
Farewell my part!”
—Sir Thomas Wyatt (1503?1542)
“Laid out for death, let thy last kindness be
With leaves and moss-work for to cover me:
And while the wood-nymphs my cold corpse inter,
Sing thou my dirge, sweet-warbling chorister!
For epitaph, in foliage, next write this:
Here, here the tomb of Robin Herrick is.”
—Robert Herrick (15911674)
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