Sheaf Theory

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4 domain-specific abstractions whose origin domain is Sheaf Theory.

• Direct image with compact support — Send a sheaf along a continuous map while retaining only local sections whose support is proper over the target open set, yielding the functor conventionally written f-shriek.
• Inverse image functor — The functor that pulls sheaves on a target space back along a continuous map to sheaves on the source space.
• Stalk (sheaf) — The local object obtained from a sheaf at one point by identifying sections that agree on some sufficiently small neighborhood of that point.
• Torsion sheaf — A sheaf of abelian groups whose every local section is annihilated by some nonzero integer.