Extranatural transformation
In mathematics, specifically in category theory, an extranatural transformation is a generalization of the notion of natural transformation.
Definition
Let and be two functors of categories.A family is said to be natural in a and extranatural in b and c if the following holds:
- is a natural transformation.
- ,, the following diagram commutes
- ,, the following diagram commutes
Properties
Extranatural transformations can be used to define wedges and thereby ends, by setting constant.Extranatural transformations can be defined in terms of dinatural transformations, of which they are a special case.