Initial algebra
In mathematics, an initial algebra is an initial object in the category of -algebras for a given endofunctor
. The initiality provides a general framework for induction and recursion.
For instance, consider the endofunctor on the category of sets, where
is the one-point (singleton) set, the terminal object in the category. An algebra for this endofunctor is a set
(called the carrier of the algebra) together with a point
and a function
. The set of natural numbers is the carrier of the initial such algebra: the point is zero and the function is the successor map.