ScalingStacks

Example 5 . [04S2]

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Example 5.

Let V⊂ℂ​ℙn+1⊃(ℂ∗)n+1V\subset{\mathbb{C}}{\mathbb{P}}^{n+1}\supset(\mathbb{C}^{*})^{n+1} be a projective hypersurface of degree dd not passing through the points [1:0:…:0],…,[0:…:0:1][1:0:\dots:0],\dots,[0:\dots:0:1]. Then V∘=V∩(ℂ∗)n+1{V}^{\circ}=V\cap(\mathbb{C}^{*})^{n+1} is given by a polynomial ff whose Newton polyhedron is

Δd={(x1,…,xn+1)∈ℝn+1| 0≤xj,∑jxj≤d}.\Delta_{d}=\{(x_{1},\dots,x_{n+1})\in\mathbb{R}^{n+1}\ |\ 0\leq x_{j},\sum\limits_{j}x_{j}\leq d\}.

Vice versa, ℂ​TΔ=ℂ​ℙn+1\mathbb{C}T_{\Delta}={\mathbb{C}}{\mathbb{P}}^{n+1} and the closure of V∘{V}^{\circ} in ℂ​ℙn+1{\mathbb{C}}{\mathbb{P}}^{n+1} is VV.

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