Genus formula for a multisection of the rational elliptic surface
= Genus formula for a multisection of the rational elliptic surface
If a smooth connected complex curve $C\subset E(1)$ satisfies $C^2=k$ and has degree $d=C\cdot F$ over the base, the <Adjunction formula> gives
$$
2g(C)-2=C^2+K_{E(1)}\cdot C=k-d,
\qquad
g(C)=1+\frac{k-d}{2}.
$$