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Canonical static concept record

Sheaf

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Summary

A presheaf on a site satisfying the local identity and unique gluing condition for every cover.

Record metadata

Carrier(s)

Axioms / constraints

Notes

This node means a sheaf of sets on a site. Sheaves valued in groups, rings, modules, or other categories are modeled by the corresponding algebraic-object nodes.

Concept sources

Incoming relations (arrows to this concept)

Each relation below ends at this concept.

presheaf + site(construction junction)Sheaf

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This is an authored directed relation from the source endpoint to the target endpoint.

Authored explanation

Require matching local sections to glue uniquely over every cover.

How to interpret this relation type

Feed several structures into a construction junction and impose compatibility between them.

Relation sources

Outgoing relations (arrows from this concept)

Each relation below starts at this concept.

SheafAlgebraic space

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This is an authored directed relation from the source endpoint to the target endpoint.

Authored explanation

Specialize to an fppf sheaf FF on (Sch/S)fppf(\mathrm{Sch}/S)_{\mathrm{fppf}}, require a representable diagonal, and require that some scheme UU admit a surjective étale morphism hUFh_U\to F.

How to interpret this relation type

Keep the existing data and select the subclass satisfying an additional law, existence condition, finiteness condition, or other property.

Relation sources

SheafSheaf of groups

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This is an authored directed relation from the source endpoint to the target endpoint.

Authored explanation

Equip every section set with compatible group structure.

How to interpret this relation type

Equip an existing carrier or structured object with additional chosen data, when such compatible data exists. Use a construction junction when several independently meaningful inputs must coexist on the same carrier or interact compatibly.

Relation sources

SheafSheaf of rings

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This is an authored directed relation from the source endpoint to the target endpoint.

Authored explanation

Equip every section set with compatible ring structure.

How to interpret this relation type

Equip an existing carrier or structured object with additional chosen data, when such compatible data exists. Use a construction junction when several independently meaningful inputs must coexist on the same carrier or interact compatibly.

Relation sources

SheafStalk of a sheaf

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This is an authored directed relation from the source endpoint to the target endpoint.

Authored explanation

The stalk is the filtered colimit over neighborhoods of the point.

How to interpret this relation type

Apply a standard functorial or canonical construction whose output is not merely a reduct of the input and is not generally an equivalent presentation of the same object.

Relation sources