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In mathematics, the Fermat curve is the algebraic curve in the complex projective plane defined in homogeneous coordinates (X:Y:Z) by the Fermat equation:
- <math>X^n + Y^n = Z^n.\ </math>
Therefore, in terms of the affine plane its equation is:
- <math>x^n + y^n = 1.\ </math>
An integer solution to the Fermat equation would correspond to a nonzero rational number solution to the affine equation, and vice versa. But by Fermat's Last Theorem it is now known that (for n > 2) there are no nontrivial integer solutions to the Fermat equation; therefore, the Fermat curve has no nontrivial rational points.
The Fermat curve is non-singular and has genus:
- <math>(n - 1)(n - 2)/2.\ </math>
This means genus 0 for the case n = 2 (a conic) and genus 1 only for n = 3 (an elliptic curve). The Jacobian variety of the Fermat curve has been studied in depth. It is isogenous to a product of simple abelian varieties with complex multiplication.
The Fermat curve also has gonality:
- <math>n-1.\ </math>
Fermat varietiesEdit
Fermat-style equations in more variables define as projective varieties the Fermat varieties.