Structure

ring idempotents functor

Notation Id⁡:Ring→Set\Id: \Ring \to \Set Domain category of ringsCodomain category of sets
This functor sends a ring RR to its set Id⁡(R)\Id(R) of idempotent elements. A ring homomorphism R→SR \to S restricts to a map Id⁡(R)→Id⁡(S)\Id(R) \to \Id(S). Among other things, it provides an example of a representable functor that does not preserve regular epimorphisms.

Satisfied properties

Assigned properties

Deduced properties

Unsatisfied properties

Assigned properties

Deduced properties*

*This also uses the deduced satisfied properties.

Unknown properties

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