In algebraic geometry, a line bundle on an algebraic variety is said to be nef (short for "numerically effective" or "numerically eventually free"), if the degree of the restriction to any algebraic curve of the variety is non-negative.
In particular, every ample line bundle is nef.
Similarly, a Cartier divisor D on an algebraic variety X is nef, if
for any algebraic curve C in X, in the sense of intersection theory.
Famous quotes containing the words line and/or bundle:
“Gascoigne, Ben Jonson, Greville, Raleigh, Donne,
Poets who wrote great poems, one by one,
And spaced by many years, each line an act
Through which few labor, which no men retract.
This passion is the scholar’s heritage,”
—Yvor Winters (1900–1968)
““There is Lowell, who’s striving Parnassus to climb
With a whole bale of isms tied together with rhyme,
He might get on alone, spite of brambles and boulders,
But he can’t with that bundle he has on his shoulders,
The top of the hill he will ne’er come nigh reaching
Till he learns the distinction ‘twixt singing and preaching;”
—James Russell Lowell (1819–1891)