Seifert form (source code)

= Seifert form
{c}
{title2=$\theta_F$}
{wiki}

For oriented curves $x,y$ on a Seifert surface, the Seifert form is
$$
\theta_F([x],[y])=\operatorname{lk}(x^+,y),
$$
where $x^+$ is a positive normal push-off of $x$.