The Stacks project

Exercise 111.59.3. Let $k$ be an algebraically closed field. Let $\ell > 100$ be a prime number different from the characteristic of $k$. Let $X$ be the nonsingular projective model of the affine curve given by the equation

\[ y^\ell = x(x - 1)^3 \]

in $\mathbf{A}^2_ k$. Answer the following questions:

  1. What is the genus of $X$?

  2. Give an upper bound for the gonality1 of $X$.

[1] The gonality is the smallest degree of a nonconstant morphism from $X$ to $\mathbf{P}^1_ k$.

Comments (0)

Post a comment

Your email address will not be published. Required fields are marked.

In your comment you can use Markdown and LaTeX style mathematics (enclose it like $\pi$). A preview option is available if you wish to see how it works out (just click on the eye in the toolbar).

Unfortunately JavaScript is disabled in your browser, so the comment preview function will not work.

All contributions are licensed under the GNU Free Documentation License.

In order to prevent bots from posting comments, we would like you to prove that you are human. You can do this by filling in the name of the current tag in the following input field. As a reminder, this is tag 0DT2. Beware of the difference between the letter 'O' and the digit '0'.