Néron-Severi group
Definition 1.
Let be a surface (an algebraic variety of dimenion ) defined over an algebraically closed field . The Néron-Severi group of , denoted by , is the group of Weil divisors on modulo algebraic equivalence of divisors (see parent entry).
Theorem (Néron, Severi).
The Néron-Severi group of a surface is a finitely generated abelian group
.