ScalingStacks

Definition 5.1 [03L7]

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Definition 5.1 Let a∈ℝa\in\mathbin{\mathbb{R}} and c∈ℂc\in\mathbin{\mathbb{C}}. Define a special Lagrangian 3-fold Na,cN_{a,c} in ℂ3\mathbin{\mathbb{C}}^{3} as follows:

  • (i)

    When a=0a=0, define

    N0,c={(z1,z2,z3)∈ℂ3:|z1|2=|z2|2=|z3−c|2,Im(z1z2(z3−c))=0,Re(z1z2(z3−c))⩾0}.\begin{split}N_{0,c}=\Bigl\{(z_{1}&,z_{2},z_{3})\in\mathbin{\mathbb{C}}^{3}:|z_{1}|^{2}=|z_{2}|^{2}=|z_{3}-c|^{2},\\ &\mathop{\rm Im}\bigl(z_{1}z_{2}(z_{3}-c)\bigr)=0,\quad\mathop{\rm Re}\bigl(z_{1}z_{2}(z_{3}-c)\bigr)\geqslant 0\Bigr\}.\end{split} (21)

    Then N0,cN_{0,c} is the translation of the special Lagrangian T2T^{2}-cone L0+L_{0}^{+} of (16) by the vector (0,0,c)(0,0,c). It has one singular point at (0,0,c)(0,0,c).

  • (ii)

    When a>0a>0, define

    Na,c={(z1,z2,z3)∈ℂ3:|z1|2−a=|z2|2=|z3−c|2,Im(z1z2(z3−c))=0,Re(z1z2(z3−c))⩾0}.\begin{split}N_{a,c}=\Bigl\{(z_{1}&,z_{2},z_{3})\in\mathbin{\mathbb{C}}^{3}:|z_{1}|^{2}-a=|z_{2}|^{2}=|z_{3}-c|^{2},\\ &\mathop{\rm Im}\bigl(z_{1}z_{2}(z_{3}-c)\bigr)=0,\quad\mathop{\rm Re}\bigl(z_{1}z_{2}(z_{3}-c)\bigr)\geqslant 0\Bigr\}.\end{split} (22)

    Then Na,cN_{a,c} is the translation of the nonsingular SL 3-fold L1,a+L_{1,a}^{+} of (17) by the vector (0,0,c)(0,0,c). It is diffeomorphic to 𝒮1×ℝ2{\mathcal{S}}^{1}\times\mathbin{\mathbb{R}}^{2}.

  • (iii)

    When a<0a<0, define

    Na,c={(z1,z2,z3)∈ℂ3:|z1|2=|z2|2+a=|z3−c|2,Im(z1z2(z3−c))=0,Re(z1z2(z3−c))⩾0}.\begin{split}N_{a,c}=\Bigl\{(z_{1}&,z_{2},z_{3})\in\mathbin{\mathbb{C}}^{3}:|z_{1}|^{2}=|z_{2}|^{2}+a=|z_{3}-c|^{2},\\ &\mathop{\rm Im}\bigl(z_{1}z_{2}(z_{3}-c)\bigr)=0,\quad\mathop{\rm Re}\bigl(z_{1}z_{2}(z_{3}-c)\bigr)\geqslant 0\Bigr\}.\end{split} (23)

    Then Na,cN_{a,c} is the translation of the nonsingular SL 3-fold L2,−a+L_{2,-a}^{+} of (18) by the vector (0,0,c)(0,0,c). It is diffeomorphic to 𝒮1×ℝ2{\mathcal{S}}^{1}\times\mathbin{\mathbb{R}}^{2}.

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