Let (
X,
L) be a polarized surface over the complex number field. Assume that
L is
k-very ample. In this paper, we study the relation between the sectional genus
g(
L) and the irregularity
q(
X). In particular we prove
g(
L)≥(
k+2)
q(
X) if
X has the Kodaira dimension κ(
X)=0, 1, or (
X,
L) is some special cases with κ(
X)=2. Moreover we classify (
X,
L) with
g(
L)=(
k+2)
q(
X) when κ(
X)=0 or 1.
抄録全体を表示