Normal degree

In algebraic geometry, the normal degree of a rational curve C on a surface is defined to be –K.C–2 where K is the canonical divisor of the surface.

References

• Sommese, Andrew J.; Beltrametti, Mauro C. (1995), The adjunction theory of complex projective varieties, de Gruyter Expositions in Mathematics, 16, Berlin: Walter de Gruyter & Co., ISBN 978-3-11-014355-3, MR 1318687