ScalingStacks

Proposition 6.7 [03LP]

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Proposition 6.7

Let a,b,c∈ℝa,b,c\in\mathbin{\mathbb{R}}. Then there exist unique functions u,v:ℝ2→ℝu,v:\mathbin{\mathbb{R}}^{2}\rightarrow\mathbin{\mathbb{R}} such that

N={(z1,z2,z3)∈ℂ3:Re(z1z2)=u(Re(z3),Im(z1z2)),Im(z3)=v(Re(z3),Im(z1z2)),|z1|2−|z2|2=a}\begin{split}N=\Bigl\{(z_{1}&,z_{2},z_{3})\in\mathbin{\mathbb{C}}^{3}:\mathop{\rm Re}(z_{1}z_{2})=u\bigl(\mathop{\rm Re}(z_{3}),\mathop{\rm Im}(z_{1}z_{2})\bigr),\\ &\mathop{\rm Im}(z_{3})=v\bigl(\mathop{\rm Re}(z_{3}),\mathop{\rm Im}(z_{1}z_{2})\bigr),\quad|z_{1}|^{2}-|z_{2}|^{2}=a\Bigr\}\end{split} (40)

is the special Lagrangian 33-fold Na,b+i​cN_{a,b+ic} of Definition 5. Furthermore:

  • (a)

    u,vu,v are smooth on ℝ2\mathbin{\mathbb{R}}^{2} and satisfy (33), except at (b,0)(b,0) when a=0a=0, where they are only continuous.

  • (b)

    u⁡(x,y)>0u(x,y)>0 when x>bx>b for all yy, and u⁡(b,y)=0u(b,y)=0 for all yy, and u⁡(x,y)<0u(x,y)<0 when x<bx<b for all yy.

  • (c)

    v⁡(x,y)<cv(x,y)<c when y>0y>0 for all xx, and v⁡(x,0)=cv(x,0)=c for all xx, and v⁡(x,y)>cv(x,y)>c when y<0y<0 for all xx.

  • (d)

    u⁡(x,0)=(x−b)​((x−b)2+|a|)1/2u(x,0)=(x-b)\bigl((x-b)^{2}+|a|\bigr)^{1/2} for all xx.

  • (e)

    v(b,y)=c−y(12|a|+y2+14​a2)−1/2v(b,y)=c-y\Bigl(\frac{1}{2}|a|+\sqrt{y^{2}+\frac{1}{4}a^{2}}\,\,\Bigr)^{-1/2} for all yy.

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