438 bytes added
, 08:17, July 8, 2008
Let <math>M</math> be a Kaehler manifold. Then <math>M</math> is Calabi-Yau if <math>c_1(K_M) = 0</math>. If <math>M</math> is a variety, we say that <math>M</math> is a Calabi-Yau variety if it has vanishing canonical class.
For example, a degree <math>n+1</math> hypersurface <math>M</math> in <math>\mathbb{P}^n</math> is Calabi-Yau. For from the exact sequence
<math>
0\to TM \to T\mathbb{P}^n \to \mathcal{O}(n+1)|_M \to 0
</math>