Generic hyperplane section of a projective curve (source code)

= Generic hyperplane section of a projective curve

For a general linear form $\ell$ not vanishing identically on a projective curve, the exact sequence
$$
0\to A_C(-1)\xrightarrow{\ell}A_C\to A_C/(\ell)\to0
$$
shows that the hyperplane-section length is $P_C(m)-P_C(m-1)=\deg C$.