Inverse System - The Category of Inverse Systems

The Category of Inverse Systems

Pro-objects in C form a category pro-C. Two inverse systems

F:I C

and

G:J C determine a functor

Iop x J Sets,

namely the functor

.

The set of homomorphisms between F and G in pro-C is defined to be the colimit of this functor in the first variable, followed by the limit in the second variable.

If C has all inverse limits, then the limit defines a functor pro-CC. In practice, e.g. if C is a category of algebraic or topological objects, this functor is not an equivalence of categories.

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