Abstract
Hartshorne conjectured that there exists a finite
number of families of smooth rational surfaces in
projective fourspace. In 1989, this conjecture was
positively solved by Ellingsrud and Peskine.
The exact bound for the degree is, however, still open.
The purpose of this talk is to construct
a smooth rational surface of degree 12.
The construction of this surface is reduced
to finding a point of a 4codimensional subvariety M
of the grassmaniann G(10,4) of 4quotient spaces in
a 10dimensional vector space.
Over a finite field with q elements,
the probability for a point in G(10,4) to lie in M
is, therefore, about 1/q^4. So we can expect to find
such a point within a reasonable amount of time
by picking points at random over a small field.
Last Updated: October 21 2004 by Hirotachi Abo
