Genus of Singular Varieties
The definition of geometric genus is carried over classically to singular curves C, by decreeing that
- pg(C)
is the geometric genus of the normalization C′. That is, since the mapping
- C′ → C
is birational, the definition is extended by birational invariance.
Read more about this topic: Geometric Genus
Famous quotes containing the words genus, singular and/or varieties:
“Methinks it would be some advantage to philosophy if men were named merely in the gross, as they are known. It would be necessary only to know the genus and perhaps the race or variety, to know the individual. We are not prepared to believe that every private soldier in a Roman army had a name of his own,—because we have not supposed that he had a character of his own.”
—Henry David Thoreau (1817–1862)
“mouth to mouth, the covers
pulled over our shoulders
we drowse as horses drowse afield,
in accord; though the fall cold
surrounds our warm bed, and though
by day we are singular and often lonely.”
—Denise Levertov (b. 1923)
“Now there are varieties of gifts, but the same Spirit; and there are varieties of services, but the same Lord; and there are varieties of activities, but it is the same God who activates all of them in everyone.”
—Bible: New Testament, 1 Corinthians 12:4-6.