ScalingStacks

Example 3.20 . [04IN]

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Example 3.20.

Let X=ℂ2−{z1z2+1=0}X=\mathbb{C}^{2}-\{z_{1}z_{2}+1=0\} and let ω\omega be the restriction to XX of the standard symplectic form on ℂ2\mathbb{C}^{2}. One can easily check that the following map f:X→ℝ2f:X\rightarrow\mathbb{R}^{2} is a Lagrangian fibration:

f⁡(z1,z2)=(|z1|2−|z2|22,log⁡|z1​z2+1|).f(z_{1},z_{2})=\left(\frac{|z_{1}|^{2}-|z_{2}|^{2}}{2},\,\log|z_{1}z_{2}+1|\right). (13)

The only singular fibre is f−1​(0)f^{-1}(0), which has the topology of a I1I_{1} fibre. It follows that this fibration is conjugate to the topological fibration in Example 2.6.

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