Nef line bundle
LINE BUNDLE ON A PROJECTIVE VARIETY THAT HAS NONNEGATIVE DEGREE ON EVERY CURVE IN THE VARIETY
Nef divisor; Numerically effective; Nef cone; Semi-ample line bundle
In algebraic geometry, a line bundle on a projective variety is nef if it has nonnegative degree on every curve in the variety. The classes of nef line bundles are described by a convex cone, and the possible contractions of the variety correspond to certain faces of the nef cone.